Johnson fed Carl Self who burst through the visiting defence to score on 69 minutes, and just 3 minutes later substitute Tom Etheridge thumped in a header via the crossbar.

Self scored his second with an emphatic strike on 77 minutes, before substitute James Clark scored a late brace, easily converting left-wing crosses from Etheridge (85 mins) and Johnson (89 mins).

Alton forced some good saves from Paul Strudley in the second half and scored a deserved consolation when Ryan Ayling followed up to score from close-range after 80 minutes.

The final will be played at Alton's ground on Wednesday May 2nd, when Thatcham's opponents will be New Inn Sports from the Basingstoke & District Premier League.