Tom Anderson wrote:

That seems really quite perverse. Is there a reason for all this?

Yes. It's because the clocks (like the standard BR/NSE 8-segment ones)
are centrally controlled. However, to make things simpler, a control
pulse is only sent once every minute (thus moving the minute hand on)
rather than once every second. Thus, the second hand is on a local
motor, and to ensure it doesn't get out of sync it's set to go around
in about 58 seconds rather than a complete minute.

The old clocks at Manchester Oxford Road are/were (not sure if they
still exist) of the same type, but without the second hand.

Neil