I have tried all the fairs outside London.(Harrogate..boring ,Wakefield OK...York OK but my favourite is the Midland at the Motorbike museum.March,June,September,December are the bigger ones when there are extra dealers. I have never left there unhappy.  no muggings on the tube plus a nice out of town location. .Well run ,fantastic facilities although a 250 mile round trip.I will be back