I'm beginning to think the same. I've heard today that if you don't want to bubble up you don't have to and you can carry on with the rules in your Tier, so as you say if in Tier1 that might suit people better.
I’ve been trying to find the same answer. I’ve read somewhere that the normal Tier rules apply for everyone during Xmas so if in T1 the groups of 6 apply. However the same article also said that was an oversight in that new rules have been brought in from 23rd Dec but old rules haven’t ended, so...