We - and I say this as another Aberdeenshire GoYer - are into winter frosts now, so I think that it is is too late to give a mature bush such a shock. I'd advise leaving the move until spring, when frosts are past. You could prune them then, too.
See what other people think.

P.S. Welcome to GoY!

I agree, potentilla is lightly dead headed/pruned early spring south of the border but maybe later in the north - ... a bit like trimming back lavender in spring. Always surprises me when they still then flower in summer. Good luck with the transplant!

Thanks very much for the advice, trouble is they have to come out now, as we are building a garage. I was hoping to save them. Maybe if I put them in the ground and make sure I cover them in hard weather. We haven't had hard frosts here yet, just a touch on the grass, a week or so ago, and now it's turned very mild and mostly damp. except for yesterday.

My advice would be different from the others - I'd move them now, as soon as possible. No harm will result if there's frost about, that doesn't matter at all, just so long as the ground isn't frozen, they'll be fine. Just try to get out as many roots intact as you can, and don't cramp any roots up in order to squeeze them into their new planting holes - adjust the depth and shape of the hole to accommodate them. And then water thoroughly - they then have the winter to settle in and hopefully should grow away nicely next year. And you will not need to provide any extra protection for them either - they'll be dormant as usual in winter. Do not, though, prune them if it can be avoided, just in case it forces new growth, which you don't want at this time of year. Tidy them up in Spring, when you can see where they're growing from.

The good news is that the forecast for the week here is for temps around 10C, so, you do have a window of opportunity before the ground freezes. Go with Bamboo's advice, because it is always good.

Cheers, everybody. I'll give it a go this week. Good news about the high temps. for the grass for our sheep too.