Bennett's surprise exit meant that none of the eight seeds reached the last 16. Swindon's Gary Harris, hoping to complete the double of English strokeplay and matchplay titles, and Colin Edwards, Bennett's international team-mate from Bath, went out at the same stage.
Wilkins, a 19-year-old Hertfordshire county player, promptly lost his next match to Mark Foster. The other two giant-killers, though, reached the quarter-finals.
Chris Poxon, who had beaten Harris, continued his winning return to the event after a 10-year gap with a 2 and 1 victory over Oliver Thomson, while Jon Loosemore, an American college product and member of the host club, followed up his 5 and 3 success over Edwards by beating Bedfordshire's Mark Wharton.
Two down at the turn, Loosemore hit back to win when his opponent sent his approach to the last hole wide of the green, his ball bouncing out of bounds into the flower bed by the clubhouse.
Poxon, whose brother, Martin, plays on the European Tour, is a 36- year-old meat trader from Sutton Coldfield and has played in the championship only once since 1977. He was one down to Thomson after 13 holes of a thrilling match, but won the next three. 'I can't play much better than that,' he said.
The best comeback was staged by Graham Homewood, the Middlesex player who was runner-up in the British Amateur nine years ago. The 33-year-old market gardener was three down to Didsbury's James Curtis with only six to play, but won four of the next five holes and halved the last to go through.
Another quarter-finalist played a part in Homewood's success. Alan Johnson, a county colleague who had won both of his matches, returned to watch Homewood and offered to carry his bag when he saw him struggling with a bad neck.