When City offered him terms of re-engagement at the end of 2005/06, it was discovered that his original contract had been secretly amended in February 2006 by Jez George.
[5] Despite an inauspicious start to his United career, hampered by studying full-time in Loughborough and a knee injury, he eventually became a fans' favourite due to his all-action style and goal scoring ability.
[8] Simpson joined Coventry City at the start of the 2007–08 season along with a host of other new players for the Sky Blues, and was immediately touted as a future star by manager Iain Dowie.
[9] Simpson scored five minutes into his competitive debut for the club in a League Cup tie against Notts County on 14 August 2007.
Ex-Coventry assistant manager Tim Flowers praised the youngster's performance, describing his acquisition from Cambridge as "a bargain" and tipping him to be a success at the club.
[10] On 18 June 2009, after intensive speculation, Simpson joined League One side Huddersfield Town for a fee believed to be around £300,000 on a three-year deal.
After being isolated from the Huddersfield squad at the start of the following season, Simpson joined Oldham Athletic on loan on 10 September 2011.
[12] Simpson scored his first goal for the club on his 13th appearance, with a free kick that was fumbled by the Burton Albion goalkeeper in a 3–1 win for the Latics in the first round of the FA Cup.
[15] On 6 January 2012, Simpson scored a spectacular volleyed strike from 25 yards against Premier League Liverpool in an FA Cup 3rd Round encounter.
[23] On 9 July 2018, Simpson signed a short-term deal to join newly-relegated League Two club Milton Keynes Dons.
[24] He scored his first goal for the club within a minute of coming on as a second-half substitute in a 1–1 home league fixture against Grimsby Town on 21 August 2018.