YHA London St Paul's - Hostel 

Stayed in a shared room for two nights - it's a hostel, a good nights sleep is never guaranteed but I slept well enough both nights. The bells at St Pauls do chime every hour on the hour throughout the night, these didn't wake me up though and I only heard them if already awake. Room was a decent size with lockers for anything you want to put away, just needed your own lock. Spotlessly clean. Was a bit worried about just one toilet & shower for our floor of two rooms but there were never any long waits and if someone was in there I just went downstairs to look for an alternative one. Towel hire cost was reasonable. Lots of places to eat nearby and not too difficult to walk to most places in London or St Paul's tube station is a five minute walk away. Would definitely stay here again and recommend!