[2][3] Son of Lieutenant-Colonel Archibald James Macalpine-Downie (died 1958), M.B.E., Royal Tank Regiment,[4] of a landed gentry family of Appin,[5] he was a King's Scholar at Eton with a focus on biology, but seriously considered a career as a concert violinist.
[2] Macalpine-Downie and his wife, Shirley Agnes (née Reid), had two sons and a daughter.
[2] The Thai Mk4 was extremely successful, winning all six races of the 1962 European 'one of a kind' regatta, in addition to the first International Catamaran Challenge in 1963.
[2] His two most famous designs were the high-speed Crossbow multihulls which set sailing speed records in the 1970s and 1980s.
Its successor, Crossbow II, set a new record in 1980 of 36.00 knots, a mark which was not surpassed till 1986.