Initially post privatisation First North Western drivers were used (I believe both Holyhead and Chester based) to work Virgin services down the coast. With the transition to Voyagers Virgin brought the driving in house at the nearest available depots, Liverpool and Crewe. Presumably given the relatively limited service (IIRC at the time it was 5 to Holyhead plus 2 to Bangor) per day it wasn't seen as worthwhile.
A Holyhead depot for drivers has been talked about for years and Avanti recently finally confirmed it was happening and advertised for qualified drivers. As Tiptoptaff says though it's all gone quiet of late.
Similarly they're meant to be opening a drivers depot at Crewe. At present, various drivers from various depots end up there during the night bringing Voyagers on and off Arriva Train Care (including one that comes back from Holyhead) - and I believe there's a fair bit of taxi work involved. It's not been advertised although one suspects there are a lot more internal candidates looking to transfer to Crewe than is the case with Holyhead..... Although there certainly used to be at least one Liverpool driver who actually lived in Holyhead and swapped on to jobs that started or finished there as often as possible!
