The bad "season" pre-dates the 4 week lockdown if you accept the Government figures.
It doesn't pre-date the distancing though, but is the problem among the likes of you and me Stolly? It seems the majority that are in hospital "with" covid are catching it there or coming from a care home.
As for the 3 month lockdown in the Spring - what did it achieve? Less community resistance almost certainly which left us more exposed in the Autumn.