Well attended with plenty of strange and unfamiliar cars, round 3 of the Vintage Sports-Car Clubs “Formula Vintage” event at Cadwell Park was interesting and entertaining.

I really enjoyed watching Mark Walker’s brilliant GN Thunderbug which provided a lot of sideways entertainment in the Frazer Nash / GN race. I can’t begin to explain the sight and sound of the Thunderbug. Watching the race at the bottom of the Mountain and I could hear every single stroke of the twin cylinder 4.2 litre engine before it came into view followed by a loud backfire as it entered the bend.

Built as a VSCC special Mark also drives it on the road, often to and from events (after fitting a silencer!). The chassis is a 1922 GN with a power unit consisting of a 1908 Riley bottom end onto which Mark has grafted two barrels from a Salmson radial aero engine. Thunderbug has a 4 speed chain drive, revs to around 1600rpm, only has rear brakes and has a top speed around 95 m.p.h.