Although Walter Tull had played in the Football League and Southern League before the Great War - making several appearances for Northampton Town against Exeter City in the process - Jack Leslie is thought to have been the only black player in the Football League during his time in the game. Aged twenty at the time of his arrival at Home Park, Jack - who had been spotted playing senior amateur football for East London club Barking Town (a similar background to Tull who had started at nearby Clapton) - took time to become established at Plymouth and didn't become a regular until the 1924/25 season when he scored fourteen times from forty league starts.

Starting 1925/26 in similar vein (on the way to finishing the season with seventeen league goals), Jack was named as one of two 'travelling reserves' for England's fixture against Ireland in Belfast in October 1925. From a distance of a hundred years the selection of a Division Three (South) player appears somewhat remarkable. However, at the time, players from lower divisions were often called up to the national team on the recommendation of a single selector or as a favour to associates within the game. A relatively recent example had been Jack Fort of Millwall, a former Exeter City player, who had made a solitary England appearance in 1921.

Consequently, given that the majority of the selectors may never have seen Jack Leslie in action, it can just about be believed that they did not know he was black. Once the discovery was made they apparently withdrew the invitation and he was never selected again.

But that was not the explanation that leaked out at the time when it was said that some of the selectors preferred the invitation to be made to an amateur player in the form of Stan Earle of Arsenal who had previously been with Clapton. Again this explanation speaks of the times when the occasional amateur player was capped at senior level on something of a 'grace and favour' basis.

It wasn't until late in his life that Jack speculated to a journalist that the withdrawal of the invitation to travel may have been on racial grounds. Over time the story began to gain credence and was aired in a book about Arthur Wharton, an earlier black footballer, in 2012. Clues from the 1920s soon emerged and a campaign started to commemorate Jack in some way. A book followed - The Lion Who Never Roared by Matt Tiller - and in October 2022 a statue of the player unveiled behind the Devonport End at Home Park almost exactly a hundred years after he made his debut for the Pilgrims. Along with the supporters' trusts at Plymouth Argyle and Torquay United, the erection of the statue was actively supported by the Exeter City Supporters' Trust. Soon after, in March 2023, Jack was posthumously awarded an honorary England cap.

Jack played on until making a final appearance for Argyle during the 1934/35 season having scored 133 times for the club in 384 league appearances. He later worked behind the scenes at West Ham United and died in November 1988 at the age of eighty-seven.