Mitten signed with Manchester United in 1936, and was in the junior side with future colleagues Stan Pearson and Johnny Carey.
[2] After the war, Mitten rejoined Manchester United and proved himself as an excellent winger during the early years of Matt Busby's time at the club.
He was part of a talented forward line alongside Jimmy Delaney, Stan Pearson, Jack Rowley and Johnny Morris, which became known as the 'Famous Five' of Old Trafford.
It was at this point that Mitten questioned the small amount of money footballers received – the maximum wage in Britain was £12 a week – compared to their evident global popularity.
This point was underlined when two other British footballers, Neil Franklin and George Mountford, signed for the same Independiente Santa Fe in Colombia, where the league had broken away from FIFA control, which meant that clubs did not have to pay transfer fees to foreign clubs, resulting in many top players from abroad playing in Colombia in a period nicknamed El Dorado.
He was, however, offered a contract by Santiago Bernabéu, the manager of Real Madrid, who was in the process of forming the all-conquering team that would feature Alfredo Di Stéfano, Francisco Gento and Héctor Rial.
Now aged 31, Mitten made 16 appearances and scored six goals in his first season at Craven Cottage, but could not save the club from relegation to the Second Division.
Initially, he enjoyed success at the club and steered the club to a pair of solid mid-table finishes, despite an ongoing power struggle between chairman William McKeag (who had installed Mitten and gave him full control over the team) and director and former manager Stan Seymour (who felt the board should be able to veto Mitten's tactics and team selections).
Newcastle gained a reputation for free-scoring football under Mitten, but they also proved to be defensively frail, and they ultimately paid the price for this in 1961, when they were relegated after a season in which they scored 86 goals but conceded 109.