It’s not illegal to move between tiers, it’s just advised against. Not sure about the Tier 4 rules though - although I expect I’ll need to know them by the end of this week. We’re Tier 3 living on the border with Tier 2. Until last week we had significantly fewer cases than our local town in Tier 2 (we’re about the same now). We shop in that local town, so cross tiers regularly. My OH sometimes works there too.
Kate Garroway-Care at home costs
Can You Name 5 More Songs? (number 2)
To obliterate your address on packaging