I have noticed that more and more people have clothmasks.
I went to a socially distanced concert last night in a large airy church, with the doors wide open. I did not see one disposable mask, everyone had cloth masks.
I suspect that those still using disposable masks are putting them in their waste bins. The virus particles will only last a relatively short time away from a human host. and there will not be enough human tissue on them to lead to the proliferation of bacteria, so it is probably no more dangerous thn disposing of paper tissue you have blown your nose into.
Estranged Son and Future Granddaughter
To think that London, or anywhere else for that matter, does not belong to any one demographic