[3] Alder's athletic career saw him compete at the 1966 Commonwealth Games in Kingston winning Marathon Gold, (having missed the 1964 Summer Olympics due to a knee injury).

He competed in the 1968 Summer Olympics in Mexico City, the 1969 European Athletics Championships in Athens and the 1970 Commonwealth Games in Edinburgh.

[6][7] He won The Great Northern Half Marathon, Belfast in 1971 promoted by County Antrim Harriers in a time of 1:05:05.

(Athletics Weekly 22 May 1971) He was featured in The Sunday Times, on 15 April 2007, which profiled his gold medal-winning run in the 1966 Commonwealth Games in Kingston, Jamaica.

[8] Later that year in October, Alder featured on the BBC One series Inside Sport and was interviewed by Ray Stubbs.