Middlesex Filter Beds #2: Urban Oasis Hackney
The cache, a flip-topped plastic tube, is hidden in the northern part of this lovely small Nature Reserve. Kindly take care to watch out for muggles who frequently pass by the cache location and please replace the cache carefully and properly concealed as (hopefully) found.
Permission to place the cache was kindly given by the reserve management agency - Lee Valley Regional Park Authority.
To reach the cache location: you can access the Middlesex Filter Beds on foot from either the east via Hackney Marshes, the west - Lea Bridge Road via the towpath (you may find space at the pub parking @ N 51 33.700 W 0 02.728) or from the north (approx 850m/15 minutes) from the car park @ N 51 33.904 W 0 02.176 at the adjacent WaterWorks Centre Nature Reserve.
The MFB are open 08.00 – 17.30 in winter and 08.00 – 19.30 in summer. Entry is free.
Step 1: the given coordinates will take you to a gate at the western edge of the reserve where you can get a glimpse of the weir. On the gate is a padlock made in a country - the alphanumeric value (A=1 B=2 C=3 etc) of the 3rd letter of which = A
Step 2: go the short distance to N 51 33.693 W 0 2.648 from where you will see graffiti on the riverside wall. The total number of (large white) letters in the two words sprayed on the wall = B
***Update 9/8/19: It seems that the graffiti has since been removed so use B=9 in the formula***
Step 3: proceed over to N 51 33.692 W 0 2.639 where the number on the Self Guided Trail post = C
Step 4: now walk to N 51 33.691 W 0 2.630 the location of an information board covering the fascinating and intriguing History of the reserve. On this you will learn that as early as 1760 there were 3 mills on this site which 'supplied over 1,000 families with water in only 1D hours'.
***Update 05/03/21: it seems the info board has gone missing, so use D=2***
Step 5: head across to N 51 33.678 W 0 2.623 where, attached to one of the large blocks of Paula Haughney's impressive 'Nature's Throne' artwork, is an identifying metal plaque on which it records its opening by JWE Jackson JP on 1 October 199E
Step 6: finally go to N 51 33.662 W 0 2.601 from where you will see a blue Thames Water plate attached to the wall. The largest of the 10 numbers on this is F55
The cache is hidden approximately 260m away at:
N 51 33.(A+C)(B-1)(F-D) W 0 2.F(C+D)(E+5)
Continues from GC7TCDY: Middlesex Filter Beds - Wildlife Haven . . .
Its isolated location makes the Middlesex Filter Beds a peaceful, timeless place, outside the urban jostle of neighbouring Clapton. Instead of traffic from the nearly Lea Bridge Road, there’s the roar of the weir – a legacy from the days when there were several flour mills on the site – and faint shouts from the famous Hackney Marshes football pitches. The sluice gate cranks and cast-iron sand hoppers that remain along the central concrete culvert and around the vast circular well head are reminders of its 120-year industrial history.
Amid the rustling reeds, wetland flowers such as pink rosebay willow herb, cuckooflower, purple loosestrife and bright-yellow coltsfoot add swathes of colour in season - over 200 plant species have been recorded at the site.
On the river, coots and moorhens nest. Over 60 bird species have been recorded in the Reserve, including reed bunting (see photo - right), woodpeckers, finches, snipe and sparrowhawks, as well as dragonflies, damselflies and butterflies. The weir is a good spot for Grey Wagtail and Kingfisher, which nest along the banks.
The brickwork of the old bed walls provides shelter for amphibians and in spring the wetlands are home to frogs, toads and newts.
The huge granite blocks that once formed the foundations of one of the old engine houses have been 
recycled as an outdoor sculpture, 'Nature's Throne', by east London artist Paula Haughney, carved in relief and arranged into a stone circle. Locals consider it their very own Stonehenge - 'Hackney Henge'!