This is an updated post:
Clock towers used to be the focal point of a village situated at a road junction or in front of a municipal building or railway station. As well as using them to tell the time of day people often chose them as a meeting place before a night out at the cinema, perhaps. There are some fine free-standing ones still around in London, plus a few on the top of some buildings and churches too. Some of them even tell the right time, even if only on one face.
Row 1: Angel; Highbury; Crouch End; Victoria
Row 2: Caledonian Market, Harlesden; Queen Mary University; Stockwell
Row3: Acton Town Hall; Leyton; Stepney Green; Lots Road