Hinshelwood was born in Oxford and joined Brighton & Hove Albion as a trainee. He turned professional in August 2002, while his uncle, Martin Hinshelwood was Brighton manager. He made his league debut on 10 August 2002 in a 3–1 victory away to Burnley, picking up man-of-the-match honours from the sports press. He made more than 40 appearances in the Championship for Brighton over the next couple of seasons, playing so well that he was selected for the England U21 squad for games against Wales and Azerbaijan in October 2004.