He helped form the Players Union in 1907 inspired after United player Thomas Blackstock died following a match and the player's family received no compensation. Appalled by this treatment, Roberts joined up with players such as Meredith and Turnbull to form a Union for footballers. It proved popular but the organisation was not recognised by the FA and subsequently Roberts never played for England again.

In 1909, the FA clamped down on Union membership. It's numbers plummetted so that the only members left were Manchester United players! The FA then suspended the United players for their failure to renounce their membership. They became known as "The Outcasts FC' in a famous team photo. It was only after Everton's Tim Coleman renewed his support for the Outcasts that the FA backed down.

After leading the Outcasts strike, Charlie was made chairman of the Association Players Football Union from 1913 to 1921. He worked tirelessly for the lot of his fellow players throughout his career and also fought against the corruption which plagued the game in that era. In August 1913, Roberts was sold to Oldham Athletic for £1,500 whom he captained to their highest League finish ever as runners-up to Everton in 1915. In 1921 he became manager of Oldham and later set up a tobacconist business in Manchester creating a cigarette which he called "Ducrobel" after the United back line of Duckworth, Roberts and Bell.

Sadly he died in 1939 at the age of 56 in Manchester Royal Infirmary after an operation on his skull to cure "dizzy spells" he had been suffering from. It has been suggested he died due to brain injuries caused by heading the old-style leather football. Charlie has his own collection of memorabilia on show at Old Trafford's museum and has an exhibit at the Museum of Labour history. He was undoubtedly a very important person in the early development of Manchester United.