He was prominent in the Fourth Test when he started his pairing with Lawry at the top of the order at Old Trafford. An Australian victory would result in a 2–1 lead and the retention of the Ashes. Their first Test stand together was not successful; Simpson fell for four as Australia made only 190. After taking 4/23 in the English first innings, removing Ken Barrington for 78 and cleaning up the tail with three more wickets, despite which England had a first-innings lead of 177. He scored 51 in the second innings in a century stand with Lawry—the first by either team in the series—which allowed Australia to reach set a winning target on the last day. Early on, England appeared destined for the target, as Dexter plundered 21 from Simpson's first four overs. However, the English batsman fell and Simpson did not concede a run in his remaining four overs. He claimed the wicket of Fred Trueman as England collapsed to be all out for 201 on the final afternoon to cede the Ashes. After the triumph at Old Trafford, Simpson had a run of heavy-scoring in the county matches before the final Test, scoring 116, 132 and 6, and 160, ending unbeaten in all but the last innings, against Glamorgan, Warwickshire and Yorkshire. He added a further 3/21 and 3/48 in the last of these matches, although the hosts still managed to hang on for a draw.