In the early years of the Richard Seaman Trophy I believe it was for pre-war Grand Prix cars and voiturettes. Dennis Poore owned and competed in an ex-Scuderia Ferrari Alfa Romeo 8C-35, which was sold to Hans Ruesch. Seaman had co-driven it to win the 1935 Donington GP. It passed to Robert Arbuthnot of High Speed Motors in Watford, who sold it to Reg Parnell, later buying it back. After Arbuthnot was killed in a road accident in 1946, Poore bought it and ran it for nearly ten years, winning the 1950 British Hillclimb Championship with it. You can find a good history of the car here:
https://www.bonhams.com/auctions/20931/lot/235/