Simpson remained undefeated in his next ten fights, and a victory over Marc Callaghan led to him receiving a shot at the British featherweight title.
Simpson lost a very close points decision as referee Phil Edwards scored the bout 115–114 in favour of Williams.
After a six-month lay off, Simpson returned to the ring to defeat former European lightweight title challenger Dariusz Snarski via a third-round knockout.
On 10 March 2007, Simpson lost a controversial points decision to Derry Mathews in a contest for the WBU featherweight title.
On 7 September 2007, Simpson fought Andy Morris for a third time and defeated him via a seventh-round knockout to defend his British title.
The fight once again took place in Middlesbrough and saw the Scotsman retain his title this time stopping Truscott in the 10th round with both fighters contesting a furiously paced bout.