The Posh director of football confirmed that the 19-year-old defender, who has been on loan at London Road since October, wil complete his move to Posh in a deal worth up to £1million on Friday.
"Ryan's deal goes through on Friday," he told the Peterborough Evening Telegraph
"It is a record transfer for the club and there are also sorts of add-ons in there as well. Things like helping Posh into the Premier League and him going on to play for England.
"If everything in the deal were to happen it could cost us £1million."