I don’t think it has saturated all households, although that is an interesting theory. I think there’s still plenty of “naive new hosts” in Kent and London
I wasn't talking about saturating all households! I was meaning that in the situation where it's more transmissible in a household, you'll get more new infections in a household of the new variant, but once that stops, you'll be the same.
ie 1000 households have CV in at the start 50% are new variant.
because the new variant is much more effective in household transmission, then 500 cases are created from that, but only 100 cases of old variant (say). This inflates the percentage of new variant cases (5/6th's of new cases here were old variant despite only 50% of cases at the starting situation) However these 600 of he cases can no longer infect other people in their household as there is no-one left in it uninfected, and the chance of test&trace (and informal tracing) working is much higher on a more transmissible variant as you're more likely to have a direct contact of someone with symptoms.
So after the initial spike, in a situation where you're locked down, you no-longer have the things which encourage lots of positive discovered cases from an index one. It wasn't about households being exhausted, just that the percentage of positives that come from a single household being different.
No idea if I've been clear.