The works I mentioned a few days ago at the junction of Ham Gate Avenue and Petersham Road continue all the way up to and in to Church Road and there are several open sections that give more of a clue as to the nature of the work.
I've called this post "water works" on the assumption that this is a pipe rather than a cable, though there is a Danger Electricity sign in the centre of the access cover. Whatever it is, it looks industrial and that is good enough for me.