I think it might be because Labour voting Londoners:
agree with and want to keep the minimum wage.
like free nursery places.
Like the government building new homes.
Like the all the equalities acts.
Like free health check ups.
Like crime going down.
They like pension credits and cold weather payments.
They like feeling like the government does actually care.
They like having more doctors, nurses and teachers, police.
and so on [there are tons of reasons].
Oh, and maybe they like foxes too.