Not sure if this is the right place to ask, but we are flying SQ into LHR T2 at 1540hrs in the afternoon. Having been in the multiple- deep queues at immigration during the early morning arrivals, we thought we'd try a mid afternoon arrival.

Does anyone know how busy immigration is (non-EU national) at that time of day?

And how does mid- afternoon compare to an evening arrival, say 7pm or 9 pm?

Thanks!