Researching the Saddleworth air crash of 1949 and the later death of Michael Prestwich, I came across this video of his father winning a motor race before the war.
It presents a wonderful picture of motor racing in the 1930s - all cigarettes and no safety precautions with commentary by Mr Cholmondley-Warner.
Henry Bryce Prestwich was a cotton merchant. A forum post on the Autosport site says:
He was born Henry Bryce Stadelbaur or Stadelbauer at Altrincham, Cheshire, England in 1911. Both spellings appear on documents. His father was Otto Stadelbau(e)r, a British subject from a Saxony family. However, like many with a German sounding name, the family changed their name during the 1914-18 war to acquire a more English sounding one (following the example of King George V).
I found that Prestwich had raced a M.G. at the Donington Park Motor Car races in May 1936 (9.5.36) and at the same track in the Coronation Trophy races in May 1937 (12.5.37). After the 1937 Cork race, he only appears once more in the records, starting but not finishing the 1938 Cork Light Car (voiturette) Race, again in a MG.
The London Gazette records that Prestwich was commissioned a 2nd Lieutenant in the British Army in November 1940.He survived the war, only to die at Saddleworth with his wife and two of his three children. It seems Prestwich was his mother's maiden name.