Some 200 local authorities in Britain are holding elections on May 5, in what many are seeing as the first vote of confidence in Boris Johnson’s leadership since partygate and the cost of living crisis. Every council seat in Scotland, Wales and London is up for grabs and there are polls across much of the rest of England. But of the thousands of seats being contested, 27 could be key to who holds power in the UK on a local scale by the time this week is out.