Stansted appeared to be very busy late last night when I too arrived back - the queues at immigration (EU/EEA only) were very long and (for some reason) the ABC trial gates were not in use.
Although I was travelling with hand baggage only and can't comment on baggage delivery, I'd have thought that the large volume of passengers was predictable given the fact that airlines publish their schedules!
Perhaps there were fewer Ryanair noshows than normal.......(just kidding!)