In message , Tom
Anderson writes

Last night, Oxford Street was closed for some sort of roadworks (and
will be until monday). I asked a workman (not one of the ones doing the
roadworks; he was just sort of hanging around) about it, and he said he
didn't know what it was for, but he thought it was a test, in some way
related to the tube. Anyone know the truth?

According to the TfL site, there are diversions due to a "crane
operation" around the Cavendish Square area - almost certainly another
giant crane going in to the John Lewis store for the rebuild.

--
Paul Terry