Snazy - your narrative says that the contractors are using pressure washers - and your picture shows no evidence of screens or any form of containment.

I have visited the site and there is evidence of areas of the walls having been stripped and there are paint flakes spread all over the subway floor.

This simply should not happen this way.

The contractor should have tested the paint before stripping to establish that there is no lead in it and/or any other dangerous material. A competent contractor would ensure his method statement would define how he will prevent material and contaminants from being released into the air and potentially poisoning the surrounding areas and people. It should also define how contaminated material would be safely removed in sealed containers to ensure that it is not left lying around - as clearly it is this evening.

I think this calls for an urgent email to Ian Ransome of LB Lewisham to ensure there is no repetition tomorrow.