Pacey striker Gayle signed a four-year contract with the Eagles in July 2013, after moving for an undisclosed fee from Peterborough United.
The Walthamstow-born man enjoyed meteoric rise in football, after hitting 57 goals in one season with Essex Senior League club Stanstead.
He quickly moved on to League Two side Dagenham and Redbridge as a trainee in July 2011, turning professional a year later after scoring 29 times during a loan spell at Conference North outfit Bishop’s Stortford.
After returning to Dagenham and netting seven times in 18 appearances, the Posh moved to sign Gayle on loan in November 2012. He made an instant impact in the Championship, scoring his first goal in the 4-1 defeat at Blackpool the following month.
That was one of Gayle’s five goals in six games during a successful loan spell – form that prompted Peterborough to shell out an initial £500,000 for his services in January 2013. Gayle finished the 2012/13 season with 13 goals for Darren Ferguson’s men, including an impressive hat-trick against Blackburn Rovers in March.