Barnet striker Liam Hatch has completed his £150,000 move to League Two rivals Peterborough United.
Hatch has been at Barnet since July 2003
The fee for the move, which was announced last week, is payable over the next two-and-a-half years.
The 25-year-old, who had also been a target for Shrewsbury Town, has scored eight times for the Bees this season.
Hatch, who joined Barnet from Ebbsfleet United for £23,000 in July 2003, recently rejected a new contract offer at Underhill.
Barnet chairman Tony Kleanthous told his club's website: "I am really sorry to see Liam go as he epitomises the spirit of our club.
"I understand why he wants to move on and make more money - we attract players as we are honourable when they get the chance to better themselves."
Hatch made his Posh debut as a substitute in their 2-1 win over Shrewsbury on New Year's Day.
Barnet have moved to replace him up front by signing Cliff Akurang from Histon.