Sometimes it's not clear when a cycle track ends, and no signage means you can end up unwittingly cycling on a pavement - possibly getting fined. (The north-east exit of Hyde Park, to Marble Arch, is an example that has caught out many who've made an honest and understandable mistake.)
So it's always good to have unambiguous signs telling you your position. Such as here, on Byward St, just north of the Tower.
It's a shared-use path for pedestrians and cyclists, without a physical separator. On which cyclists are not allowed. With a physical separator between the path for pedestrians and cyclists.