Just got a call from the shop. Apparently the connectors on the loom side of the regulator were knackered (though I thought I checked them... so when I pick up the bike I will see what I missed).. And also, the new regulator itself is a dud. So they are taking a video of it so I can use as evidence to get my £ back... The company that supplied me the regulator should be OK with it though, as the shop is replacing it with one from the same company I purchased from and they have good reputation.
Regulator won't arrive until tomorrow and I will not be able t collect until Thursday afternoon... So to London by train this time.