Simpson made his debut for Middlesex. It was the 2011 season that brought him wider attention, as he collected nearly 900 runs at an average of 43.
As well as being a capable gloveman, he has played several innings that decided matches in Middlesex's favour. One was a hundred against Hampshire. Another was a crucial knock at Taunton that helped the county claim the Championship, ending a wait of 23 years for that title.
Outside Middlesex, Simpson has also turned out for the Marylebone Cricket Club. He has passed 5500 runs in first-class cricket, where his average stands at 30. He has a broad array of strokes and has shown himself to be a useful batsman in every format of the game.