I'm slowly visiting different ice wells and ice houses in the Greater London area. This one near Eltham I saw the sign as I was passing on the bus, so stopped for a visit. It is actually by Mottingham station, and is located at the edge of The Tarn, which is an area of woodland and parkland.
The ice house was for Eltham Lodge which isn't that close, but the Tarn was then part of Eltham's Great Park. It is now part of The Royal Blackheath Golf Club.
The ice well is located north of the lake, where the word "The" is on the above map. It was built between 1750 and 1760. Eltham Lodge was built in 1664. The ice was cut from the lake and placed in the well, which was brick lined. The entrance faces north to give it shelter from the sun. The whole construction would have been thickly insulated with a conical straw thatch covering. And it is located in a shady and damp part of the wood.
A section has been removed to allow visitors to look into the well.