 His career at Walsall faltered, and he was allowed to join Cambridge United for £22,500 in the summer of 1997.A prolific spell at the Abbey Stadium prompted Reading to pay around the £750k mark for his services in February 2000.Butler scored on his debut against Preston North End and continued his goal-scoring form – including a goal in the 2000–01 Football League Second Division play-off Final in May 2001, although Reading went on to lose the match 3–2 to Butler's former team Walsall.