The highly rated 23-year-old, who played for England from under-16 to under-19 level and is a current Maltese international, is a versatile defender who can play at right-back or in the centre.
Having come through the youth ranks at Portsmouth, he had a trial at Liverpool before signing for Queens Park Rangers, then playing on loan for Nuneaton Town and spending 2014/15 in Crystal Palace’s reserves.
He joined Dover in the summer of 2015 and spent the last two seasons as a regular in the Whites defence, helping them challenge for the National League play-offs in successive seasons.
His excellent form at Dover has seen his stock rise and he has been linked with numerous clubs this summer, including Hibernian, Motherwell, Lincoln City, Fleetwood Town and Bradford City.
Fleet boss McMahon can now head to Portugal and plan pre-season with his squad largely in place ahead of the big kick-off on August 5th.