Normally known as Willie or Billy, Peterhead, Aberdeenshire born winger William Aitken began his football career with Kirkintilloch Harp in 1912 and played for Kirkintilloch Rob Roy in 1913, and Kilsyth Rangers in 1914 before joining Scottish amateur club Queen’s Park in 1916, making his Scottish League debut in a 2-2 draw with Dundee at Hampden Park that September. He scored a hat-trick in a 4-2 win at Airdrieonians in August 1917 and another in December in a 5-0 win over Falkirk, scoring 14 goals in 62 appearances for The Spiders before joining Rangers in 1918. After 2 goals in 21 appearances for the Ibrox club in 1918-19 he moved south to join Second Division Port Vale along with Peter Pursell for £500 in 1919, making his Football League debut against Tottenham Hotspur in October 1919. His single season at The Old Recreation Ground saw him score 4 goals in 31 appearances for The Valiants.
He was sold on to Newcastle United for £2,500 in May 1920, and played for the Anglo-Scots representative side in 1921. He spent four seasons at St James’ Park, although despite playing in two earlier rounds he wasn’t selected for their victorious 1924 FA Cup Final team. After 10 goals in 110 appearances for The Magpies he joined Preston North End for £1,000 in July 1924, and was a near ever present for The Lilywhites in 1924-25, missing only one game. After two seasons at Deepdale, having scored 11 goals in 58 appearances, he joined non league Chorley in September 1926, but returned to Football League action three months later signing for Norwich City. He made 14 appearances before the end of the season before joining non league Bideford Town.
He travelled to Italy in 1928, and impressed Juventus chairman Edoardo Agnelli with his idea of exporting the playing system pioneered by Arsenal manager Herbert Chapman, becoming their manager. However, not everyone was convinced by his new methods, and some “Juve” players were unwilling to put in the extra work required to make the system work. He nevertheless led the “Old Lady” to a third-place finish in 1929-30. Though he found little success at Stadio di Corso Marsiglia, his methods were built upon by future coaches at the club. He was unable to take to the field as player, as foreigners were not permitted to play in the Italian leagues. He eventually ended up playing and coaching football in France for AS Cannes, Stade de Reims and FC Antibes between 1932 and 1939. At Cannes he was part of the team that reached the Coupe de France Final at the Stade Olympique Yves-du-Manoir on 24th April 1932, which they won 1-0 over RC Roubaix. They also finished as runners-up in the Ligue de Football Professionnel in 1932-33. With Stade Reims, he won the Championnat de France amateur league in 1935.