I've been talking to more and more British people who use addresses of friends and relatives here, and Irish people who use addresses of friends and relatives in Britain or the north, when dealing with issues outside the jurisdiction within which they live.
Personally, I'm among them. Talking to a few friends over last weekend, most of them do the same, and have suitable contacts.
Methinks neither Leo nor Boris will get quite the cut they might have hoped for. I certainly hope so.