On 20/09/2020 20:04, Graeme Wall wrote:
On 20/09/2020 14:43, Basil Jet wrote:

https://goo.gl/maps/vsrHwfozntYeUxoG7

This is nowhere near the Crossrail alignment, BTW.

Standard OS survey?

I don't think so. They seem very interested in one particular building.
The Secchi disk-like fiducial markers are stuck on with masking tape,
which means they are expecting movement in the space of a few hours...
the retroreflectors used for monitoring movement during the Crossrail
project were all screwed on so that movement over several weeks could be
monitored. I imagine they were enlarging a cellar, but the whole thing
looks a bit ramshackle with fiducial markers blowing in the wind and
theodolites prone to being knocked by a dog or pigeon.

--
Basil Jet recently enjoyed listening to
Soft Machine - 1971 - Fourth