It's a hornet mimic hoverfly, possibly/probably one of the Volucella species (inanis or zonaria?). The experts can probably say which but roughly how large was it?
Fyi, here's a great example of V. inanis in this thread : http://www.nhm.ac.uk/natureplus/message/50306#50306
Yep, it's another fine example of Volucella inanis.
Volucella zonaria has much broader black bands and a chestnut coloured thorax, also are generally more orange than yellow-ish in colour. Both lay their eggs in the nests of social wasps where their larvae feed and develop on the 'midden' within the nests and also to some extent on the wasp larvae themselves.
It is one of our largest and colourful hoverflies - always a joy to see.