My OH worked at Martin's in Colwyn Bay for a while around the early 1960's and I'm always amused by her telling of all the various banks sending their messengers to swap cheques.
Yes Yorkie, this was called the local clearing system as opposed to the national system in London. The local system basically operated in towns where most of the major banks had a branch within 'walking' distance of each other. At the end of the working day, each bank would separate those cheques drawn on local banks which it had collected from its customers paying them in, and instead of sending them off to London would do the "swopping" on the following working day locally. That way local cheques cleared the following day as opposed to taking 3 days or more.
The local system I think from memory, ceased around the early 1970s.
BTW Did you know that the main cheque clearing system located to Trentham Gardens during the second world war - there is a plaque there in the gardens with the details. Perhaps they sorted the cheques while the dances went on in the ballroom!!