Caretaker manager
When he arrived at Swindon Town in November 1994, they had recently been relegated from the Premier League and were battling against a second successive relegation. McMahon joined them as they were preparing for a League Cup match with Derby County. Caretaker manager Andy Rowland picked the team, and the Town progressed to the next round. McMahon took full control for the next game – a league match at Southend – and he picked himself in the starting line-up. The Town lost 2–0, and McMahon was sent off. His first victory came with a 2–1 scoreline against top-of-the-table Middlesbrough.