So you're renting out a flat that you're 'managing' for somebody else, presumably the owners. Are they OK with their property being used for work by prostitutes? I can't imagine working from a flat in such a small block would stay unnoticed for long at a time when people are at home a lot more of the time either, but that depends on the layout/entrance arrangement.
Either way, you need to post detailing the rent and also the nearest tube station - there's no point in wasting your time or ours if the place isn't what somebody is looking for.