By chance, an invitational Northern Ireland Trophy was staged shortly after Allen turned professional. As a local player, he was invited and made an immediate impact, defeating Steve Davis and John Higgins to reach the quarter-finals, before losing to Stephen Hendry. In his first year on the tour, he reached the last 32 of the 2005 UK Championship and the 2006 Welsh Open, losing 2–5 to the then World Champion Shaun Murphy after leading 2–0. He also got to the final qualifying round of the 2006 World Championship, losing 7–10 to Andy Hicks, after leading 7–4.