The wording Grayson used was ambiguous:
"Pre-contract agreements aren't binding so both parties could pull out at any time. If he bangs in another 20 goals, there might be bigger teams than Everton coming in for him."
Perhaps it means Leeds and Everton need to agree that Beckford could go elsewhere?
Also, maybe it's one of those pre-contracts that can be sold to another club like a bond!