There's a time signal broadcast from Rugby, UK, and you should be able to find "motor" modules which pick this up. It may be possible to retrofit these to your clocks but I suspect that mounting and fitting hands will be problematic - unless there are some standard sizes that I'm not aware of.
The signal, also known as the MSF signal (and formerly the Rugby clock), is broadcast at a highly accurate frequency of 60 kHz and can be received throughout the UK, and in much of northern and western Europe. The signal's carrier frequency is maintained at 60 kHz to within 2 parts in 1012, controlled by caesium atomic clocks at the radio station. Source: Wikipedia.*
The article goes on to explain the time encoding which is also transmitted on the carrier. This is used to synchronise clocks and clock systems.