White, Compton and Hamilton get fixed up.
John, who spent nine years in the U's first team and made over 250 appearances for the club, has signed for Essex neighbours Southend United on a two year contract.
John graduated through the U's youth team, but will now play his football at the other end of the county after joining the team where he had previously had a short loan spell.
Meanwhile, Jack Compton, who joined the U's in January on a short term contract until the end of the season, has headed north. He has signed with Hartlepool United, linking up with new boss Colin Cooper, who had previously had Jack at Bradford in his short time at Valley Parade.
Completing the trio of former U's on the move, Bradley Hamilton has gone to Conference South new boys Concord Rangers. Bradley will come up against Chelmsford City, with whom he finished last season.
We wish all three players the best of luck at their new clubs.