His ton made him United's all-time top scorer until Sandy Turnbull reached treble figures in 1914. It also made him a valuable asset, a point not lost on Newton Heath's cash-strapped directors when a bid came in from across town. Reluctantly, Cassidy was sold to Manchester City in April 1900 for £250.
City made a loss on Cassidy 12 months later when they sold him to Middlesbrough for £75 after a disappointing season.
He fared better at Boro, scoring 34 goals in 135 games, but clearly his best years were behind him - those he spent as a Newton Heath hero.