A date to add to your calendar for this year is Sunday 20th September. It's already the 6th time that this event has been held and I've not been to one,only hearing about it last year from Adam of Italian Motor magazine - see his blogspot posting for 2014 for plenty of pics.
Weather permitting it looks to to be a great day out with plenty of Vintage and Classic Bikes,Cars and Aeroplanes in a great setting of a 348 acre former RAF Bomber Command base.
From here in Bristol there are some pretty good roads via Tetbury and Cirencester into Oxfordshire and Bicester is close to the M40 making for easy access from more Northerly routes.
According to the limited information currently on the Bicester Heritage website it is open from 9am until 2pm
One pic lifted from Adam's blog from the event last year