Caught the eye of Essex when he made 84 and took three wickets for Yorkshire in a Championship match at Chelmsford in 2001. Joined the County before the start of the 2002 campaign to replace Peter Such in the off-spin department. Became a vital member of the one-day team and also took advantage of some favourable pitches as the 2002 Championship season progressed. Followed that up as the only Essex player to take 50 Championship wickets during the 2003 season. The next campaign saw the Yorkshireman press his claims for all-rounder status with a maiden Championship century against Somerset in May. Another productive year in 2005 pushed calls for a place in the England ODI squad on the back of 18 wickets in the totesport League and some useful contributions with the bat as Essex lifted the title. Only four bowlers claimed more wickets than Middlebrook during the 2006 C&G Trophy competition while his batting highlight was a Championship century against Division Two champions Surrey at Colchester. Wickets proved harder to come by in 2007 but he did manage a Championship century at Lord’s.