Tucked between the two Leas in Hackney, the old river Lea the Saxons and Danes fought over , the boundary between Danelaw and Saxon Mercia , and the 18thC canalised River Lee Navigation, just south of Lea Bridge in the Middlesex Filter Beds Nature Reserve, stands an unusual granite sculpture called Nature’s Throne, surrounded by the granite Hackney Henge! 
The VADS Visual Arts Data Service describes it as ” … ten granite blocks in a circle surrounding a huge stone seat. This central double seated throne is fashioned from five stones and is carved with natural motifs. The north facing seat celebrates the water aspects so central to the site, the south facing seat celebrates the sun and earth. Images of natural life are carved in relief. The granite standing stones are not carved but retain the holes and marks of their previous industrial use. All 15 blocks were retrieved from the foundations of ’Victoria’, a massive Cornish beam engine, installed on the site in 1859.” 
Nature’s Throne and the Hackney Henge were created in 1990 by Bromley-by-Bow based sculptor Paula Haughney though the plaque has not lasted as well as the granite!  
The massive lumps of granite, imported from Cornwall, were part of the base of the Victoria Beam Engine  that was also imported from Cornwall, built by Harvey’s of Hayle  to pump water for the East London Waterworks Company.  The Cornish engine was designed to pump water from the filter beds up to reservoirs.  And it needed a strong, and that meant granite, base as it was apparently “At the time of its erection in 1855, … the largest machine for supplying water to towns ever constructed.” 
The East London Waterworks Company was established in established in 1806 and built the filter beds by 1850  but clearly something went badly wrong with the filtering process as only a few years later in 1866 the company were found guilty of creating a cholera outbreak that killed nearly 6000 people from pumping out of contaminated water from the Lea. 
The granite is known to be from from Cornwall and maybe from 1 of the quarries I have featured! It is rich with white feldspar but without any obvious large crystals indicative of some of the Cornish granites. I will not hazard a specific origin but will try to find out! 
As I mentioned above the The River Lea was for some decades an important internal border in the British isles established by The Treaty of King Alfred and King Guthrum between the Saxon Mercia and the Viking East Anglia in 890,  and the site of numerous battles famously one around Ware in 985 when it is said Alfred diverted the river so the Viking fleet was stranded.   And less than a mile to the south on Hackney Marsh, grows a large clump of the shrubby Elder, Danewort, or Danesblood, Sambucus ebulus, a plant ‘it is said’ flourishes where the blood of Danes was shed! 
As well as Nature’s Throne and the Hackney Henge , there lots else to see at the Middlesex Filter beds and the neighbouring Essex Filter beds and even though a large area is still being used commercially there is a campaign to have it turned into another public area.  In the inaccessible area are remains of the Triples Engine House, with massive granite stones still to be seen,  and the base also of another long gone massive steam engine, the Princess Engine  and lots of other public art to look out for 
Geologically, and I’ll be doing a separate blog post the filter beds have some great setts!
Middlesex Filter Beds itself are now managed as a nature reserve open to the public –
“Come and visit and you may well see toads, frogs and newts, dragonfly and damselfly, plus over 60 different species of bird. The filter beds also boast Paula Haughney’s monumental Nature’s Throne, made from huge granite blocks salvaged from an old engine house.
With a variety of habitats the filter beds provide interesting wildlife throughout the year. The wooded areas are excellent for flocks of tits and finches. Look out for Great Spotted and Green Woodpecker. Kestrel and Sparrowhawk are found on the reserve and will also hunt on the adjacent open grassland of Hackney Marshes.
The brickwork of the old bed walls provides shelter for amphibians and in spring the wetlands are home to frogs, toads and newts. The weir is a good spot for Grey Wagtail and Kingfisher, which nest along the banks.
More than 200 plant species have been recorded including Cuckooflower and Purple Loosestrife. There’s also a community of interesting mosses and liverworts along the old walls of the beds.” 
Hayle, nowadays more famous for the fantastic Gwithian beach, on which I saw the 2000 solar eclipse, is no more than a very small town, but in the mid 19thC was an engineering powerhouse! I’ve driven past the site the pump was manufactured, and the quay it would have been shipped to Hackney from, many times while driving through Hayle, without a clue as to that historical link to Hackney! 
And a last thought. The Leabridge.org.uk is now only available from web.archive.org which is a great shame as it’s an outstanding piece of local history. I hope that on archive.org it is secure. For more information on the area see also https://www.saveleamarshes.org.uk/
Getting there: Middlesex Filter Beds are just south of Lea Bridge, past the Prince/ss of Wales pub, with numerous bus routes and within walking distances of Clapton and Lea Bridge railway stations. Coming from the Leyton side there are great cycle paths.