It has been said that the largest amount of the Old London Bridge [ see https://buildinglondon.blog/2022/02/15/30-old-london-bridge-part-1/ ] that was to be re-used ended up down the Thames at Greenhithe in North Kent, for the building of Ingress Abbey and maybe some local walls, and some other bits and pieces, as noted by the Londonist and others. However there is some debate! Read on!  
There had been a building on this beautiful site, overlooking the Thames, with soft chalk hills behind, since the 14thC and for many years farmed by a convent, but in the early 19thC the 16thC house occasionally used by Henry VIII as a countryside get-away, was demolished for a plan to build an enormous Royal Dockyard there. In the end it was decided to expand the Royal Shipyard at Deptford instead and the now mainly cleared site was bought from the Admiralty by City of London Alderman James Harmer, a radical lawyer, of whom more about below, who had Ingress Abbey [never an actual abbey] built in 1833.
The extravagant ‘Tudor-Gothic’ house was, and is again now, stunning but sadly after many decades as a part of a sequence of Naval Colleges, it was abandoned and fenced off in 1970 ending up semi-derelict by the early 2000s. It was then restored as part of a very large, up-market housing development on the old estate, much of which had for most of the 20thC been a vast paper mill, and is now again privately owned and bizarrely doubles as the Lithuanian Consulate. 
There’s lots of suggestions that at least most of the stones were from London Bridge, and of course it would have been pretty simply to barge them downstream on the tide to Greenhithe. And with his City connections I suspect Harmer would have been able to buy the stones pretty cheaply, both the newish Portland Stone and the older Kentish Ragstone. John Times writing in 1872 in his ‘Abbeys, castles, and ancient halls of England and Wales; their legendary lore and popular history’ states Harmer bought stones from a colleague Alderman – “A portion of the stone [ of London bridge ] was purchased by Alderman Humphery, and by him sold to Alderman Harmer, who employed it in building his seat, Ingress Abbey, at Greenhithe, in Kent.” 
This quote is similar to the one in ‘History of the Tower Bridge and of other bridges over the Thames built by the Corporation of London’ by Charles Welch in 1894 which stated “A portion of the stone was purchased by Alderman Harmer and used in building his seat, Ingress Abbey, near Greenhithe” indeed to have been simply copied but missing out the middleman! 
But as with so much of these historical buildings the literature is unclear of what exactly Ingress was and is built from. Historic England are typically vague as to the geology, stating only that “ It is supposed to have been constructed of stone from the Old London Bridge….The house is of ashlar with a slate roof.” which is not very precise, though at least ashlar is not going to be ragstone by definition. Their wording is the same as the Kent County Council description so I am not sure who wrote this.  
An article in Kent Online states “ Ingress Abbey was designed by the architect, Charles Moreing and is said to have been made using ragstone from the Old London Bridge and Houses of Parliament.”  but provides no reference.
And a ‘History of Ingress Abbey –Greenhithe Kent’ drawn up by Pandora International Limited, who owned the building after it was renovated in the 2000s, states not only that it was built “… entirely of portland ashlar, traditionally explained by the fact that the stonework of the old London Bridge, demolished in the previous year, was re-used in its building…” but quotes an article from the Times of 1997 stating “Most of the construction of the walls were of Kentish rag stone which was externally faced with Portland Stone unusual in a county house in the 1830’s.” but then asking the question “ Is it possible that the walls were of an earlier date?”
I would think that it’s certainly possible that Old London Bridge had enough Portland Stone AND Kentish Ragstone to build a new house and as London Bridge itself was made of Kentish Ragstone and faced with Portland Stone in the 1760s renovation and widening, this could quite possibly have been replicated at Ingress. 
But… a document by the Harmer Family Association, 2009, states categorically “Ingress Abbey is not built from the stone of the old London Bridge. When Alderman James Harmer bought Ingress Park the old house had been mostly pulled down, but what was left was incorporated into the left wing as you look at it, the rest of the house was built of brick rendered with cement as was confirmed during the recent building work. James Harmer did buy some of the old medieval London bridge stones but investigations by AOC Archaeology on behalf of Crest Nicholson prior to restoration revealed that Kentish Ragstone from the old London Bridge was used as core stone in the middle of the structure and on the London road perimeter wall.” 
But looking at the building from the outside it does not look like at least the front and west side are cement render though I say this as not being able to actually look closely.
The AOC Archaeology investigation mentioned states “It is thought that part of the old house forms the eastern wing of the current Ingress Abbey, since this was rendered, not clad in stone and flint.” 
I have communicated with Les Capon at AOC who carried out the survey though he notes that AOC only looked at one side of the building. He states “I do not think the rest of the materials of the house; the Ragstone, Flint and Portland stone are likely to have came from London Bridge, they fit too well to the building and looked fresh.”
This makes sense though equally, the Portland stone would have only been from the 1760 rebuilding so not that old so could still today look fresh as do many other old buildings in London made from Portland stone. The flint certainly would have been local and I guess it’s a toss up whether getting ragstone from Maidstone, not so far away of London Bridge made more sense or was cheaper.
However. The MOLA monograph on London Bridge also doubts that Ingress was built from stones from the 1830s demolition. They say there is no documentary evidence to suggest it but they then also note that James Harmer was on the London Bridge Demolition Committee, which to my mind suggests he could officially have procured some stone, and also that a lot of stone went missing and they suggest that “perhaps some of this .. ended up at Ingress Abbey”. 
It does seems clear then that some of the structure predates 1833, but also that the building does seem mainly to have been built with Kentish Ragstone faced with Portland Stone and that both had been used to face London Bridge in 1760 and that vast amounts of both stone would have been available to Harmer, from logic alone I suspect Ingress Abbey is indeed built with at least some stone from London Bridge!
The estate walls
In terms of the estate walls being Kentish Ragstone, they do look the part [ see https://buildinglondon.blog/2022/03/10/33-old-london-bridge-at-wandsworth-common/ ] but then again Kentish Ragstone looks like Kentish Ragstone anywhere, whether medieval or 19thC!
The Londonist suggests that we “… head to the A226 and you can sit on a piece of the medieval London Bridge” though tbh it’s usually a pretty noisy, busy, dirty road so you might not want to sit there very long! 
The Royal Naval College Building
The good news is that regardless of what it is built from Ingress Abbey stands again scrubbed clean and white as when it was built. But there was in my opinion a scandalous demolition in the 1990s of a building on Ingress Park before the site was comprehensively re-developed.
From 1871 Ingress Park was also the site of the Incorporated Thames Nautical Training College  with it’s massive wooden Training Ship HMS Worcester moored in the Thames, accompanied for a number of years by the Cutty Sark. 10s of 1000s of naval recruits passed through here. From 1922 Ingress Abbey was used by the TNTC as a shore base.
In 1968 the TNTC became part of the new Merchant Navy College and for that in the mid-1976 an extraordinary, unique, modernist building was opened. “The college ashore was designed and built (and rebuilt) during the years 1974-75 by the Inner London Education Authority ILEA, opened officially on Thursday 28th October 1976 by Prince Philip, and trained Deck, Engineering and Radio students for the Merchant Navy before closing in 1989.” 
I absolutely love it and am really shocked that it was demolished in the 1990s before the redevelopment of the site, and I can’t work out who by or why. An absolute tragedy in my opinion.
There is a photo of it, derelict, here, in 1998 
The Building London blog also always likes to find some interesting radical angles to the posts and Ingress Abbey scores highly!
Not only was it the home to radical lawyer James Harmer but also to Chartist poet Eliza Cook!
James Harmer was born either in Norwich or London and his father was a weaver in Spitalfields, dying when James was just 10.  
Bought up by his mother he ended up as one of the foremost radical lawyers of his era, defending for example nationally important radical Samuel Bamford on charges of treason after the Peterloo Massacre of 1819.  as well as the Cato Street Conspiracy  accused include black Jamaican radical William Davidson  and opposing the death penalty. Harmer stated that the ‘Criminal Law’ “ …affords much less security to life than the rest of our laws do to the most insignificant property”. 
Harmer became an elected City of London Alderman in the 1830s but was later blocked from becoming Mayor of London due to his radicalism and ownership of the radical paper the Weekly Dispatch. The Bishop of London attacked him, accusing him and his Weekly Dispatch of wanting to “…subvert the whole of our social structure, and to revolutionize the property, the laws, the morals and the religion of this country”  Sounds good!
[ Ironically the Weekly Dispatch and later the Sunday Dispatch became in the 20thC the biggest selling Sunday paper and strangely continues to this day after being merged into the Sunday Express who would no doubt concure with the Bishop of London rather than Harmer! 
Harmer moved away from Ingress to Cricklewood, where he was to die, after attacks of ‘ague’ or malaria, which was endemic in Britain’s marshlands, as much of the Thames coastline was till the late 19thC. 
Equally, indeed maybe more, interesting was that one of the residents of Ingress Abbey in the 19thC, as a guest of James Harmer, is the awesome but largely forgotten poet Eliza Cook.  Cook was born in London in, variously 1812,17 or 18 to a brass or tin-plate worker [ tenuous link! my paternal grandfather was a tin-plate worker in Tinopolis aka Llanelli! ] and became a poet as a teenager with several of her poems becoming standards in popular anthologies.
But. She was also a Chartist and a feminist and as a contributor to various radical journals in the early/mid 19thC she had became friends with the editor of the Weekly Dispatch, James Harmer, see above, and ended up staying at Ingress Abbey for a number of years.
Debapratim Chakrabarty in his study ‘The Chartist Poetry of Eliza Cook’ in The Confidential Clerk states “Hailed by her contemporaries as the ‘new Burns’, Eliza Cook (1817-1889) was, in her lifetime, the most prominent woman poet from the working class of England. Though she was never employed as a farmhand or factory worker she belonged to a working class family, her father being a tin-man and brazier. She was self-educated and self-directed, making a virtue of this, presenting herself as a poet for the people whose credentials were an innocent wisdom and an honest sentiment. A radical and Owenite socialist in thought, she committed herself to the mission of ‘leveling up’ her fellow working men and women” 
I particularly like her poem ‘They All Belong to Me’  with it’s similarities to Woody Guthrie’s This Land Is Your Land 
“I care not who hold leases, Of the upland or the dell,
Nor who may count the fleeces, When the flocks are fit to sell.
While there’s beauty no one can barter, By the greensward and the tree: Claim who will, by seal and charter, Yet ‘they all belong to me’.”
And just maybe seminal Oi band Cock Sparrer was influenced by Cook’s poem with their 1982 Oi classic ‘England Belongs to Me!’ 
“England belong’s to me
A nation’s pride the dirty water on the rivers
No one can take away our memory
Oh Oh, England belongs to me”
Cook also wrote a poem to support the Chartist Petition of 1848  , ‘A Song: To ‘the People’ of England’ … eulogizing the Chartists as the “representatives of ‘Liberty and Reason’…[as] … the English counterparts of the revolutionaries in France, Italy and the rest of Europe.” though clearly on the side of reform not violent revolution!
“Meet Oppression, face to face!
Not with weapons red and reeking;
Not with Anarchy’s wild flame;
But with love and open speaking,
In “The People’s” mighty name!”
I also found it particularly fascinating, that Cook, not only having the first journal to be named after a female, saw how music is a key part of working class culture and emancipation.
Susan Rutherfords’s “Loud and Open Speaking in ‘the People’s’ Mighty Name”: Eliza Cook, Music and Politics” states “In 1849, the working-class poet Eliza Cook (1818–89) expanded her international profile by venturing into weekly periodical publication with Eliza Cook’s Journal. Not only was this the first British journal named after a female editor but it also placed an unusual emphasis on music—unusual not least because few women in that epoch were given the opportunity to participate in the broader critical discourses on music. Cook’s poetry was already widely disseminated through various musical settings by composers from William Balfe to Henry Russell; in her new journal, music further emerged as central to her philosophy of liberation for all. Placing street musicians alongside opera and salon concerts in an exhibition of remarkably eclectic taste, Cook saw the propensity for music making in all layers of society. She regarded musical culture as a soundscape of experience, emotion, and agency to which she, and all those from the laboring classes, not only had a right to access, engage in, and share but was part of their own innate being. Music symbolized imagination, freedom from the mundane, and limitless human potential. Efforts to secure music for “the people” were thus indissolubly linked to broader political rights for suffrage and equality.” 
Visiting / Getting there
Ingress Abbey is easy to get to with public transport from London.
The simplest way is by train from London Bridge to Greenhithe and then a 10 to 15 minute walk
More interestingly get a fast train from Kings Cross International and Stratford International to Ebbsfleet then a walk across the Swanscombe Marshes, currently the battle ground between locals and a vast planned, but looking increasingly doomed ‘London Resort’ theme-park.
See https://www.saveswanscombepeninsula.org.uk/ for more details
The whole area is well worth a trip out of London. Immediately around Ingress Abbey are a series of 18th and 19thC follies and caves, with a Heritage Trails sign-posted, high chalk cliffs behind from long abandoned quarries while the other direction the stunning views of the wide Thames looking across to Essex.
See these links! https://sebastiansswagger.wordpress.com/2018/06/19/tunnels-at-ingress-abbey/
 The Hanging Tree: Execution and the English People 1770-1868 https://books.google.co.uk/books?id=mqG8a74SkRMC
 Malaria in the UK: past, present, and future T Chin, P D Welsby https://pmj.bmj.com/content/80/949/663
 “Early Roman features, possibly defensive, and the modern development of the parkland landscape at Ingress Abbey, Greenhithe” Les Capon AOC Archaeology 1998-2004 published in https://www.kentarchaeology.org.uk/Research/Pub/ArchCant/129-2009/129-01.pdf
 “London Bridge 2000 years of a river crossing” Bruce Watson, Trevor Brigham and Tony Dyson, Monograph 8, Museum of London Archaeology Service, 2001