How big is it? Could it be a rail/girder/hairpin socket, though you'd expect a couple of rows of them?
thank you for your thoughts just odd never seen anything like it on the London streets before they are all lined each side of the road about 12 yards apart on the pavement about 2ft 6" x 2ft 6"
Appropriately for London, I'm going to have a wild stab at coal holes. If they're Victorian houses they might have coal bunkers in the cellars. Do the Roman numerals tally with the house numbers?
Put on a hi-vis jacket and a hard hat, then try to lift one off (...no one will challenge you if you are dressed for the part!). Concrete covers often cover metal covers (e.g. when a path is now higher than the original level of he path) so its probably a sewer cover, although rather a strange shape.
They don't seem to be sufficiently photogenic for the manhole photographers to have bothered with them so far. Unlikely to be coal holes as they are nothing like any I've seen and don't really look as though they are intended for frequent opening
True - but when out you need to have a change of clothes, that white 'uniform' is a dead give away , wear a kilt or something similar so you blend in more TD
At least you are not alone: Britain's first 'drain spotter' spends his life taking snaps of sewer covers | Daily Mail Online
There is a special Google search feature that you may or may not be familiar with: Google Image Search. This is where you upload your photo and the search engine tries to find similar images. It didn't find a matching inspection cover for your photo when I tried it. But I then uploaded the cropped section from a recent photo of the Port Sunlight war memorial (attached), and it presented an image of the memorial within the first 300 photos returned. It is, what it is. But this technology is improving all the time, so may be useful at some point in identifying locations or objects for some of you.
A similar service is Tineye TinEye Reverse Image Search They claim not to keep copies of any picture you upload.
I just had a look at it, but I think it only finds exact image matches (pixel by pixel) so I guess its good for checking if anyone is using your images.
