Doyle was signed from Cardiff on a season long loan but it was reported atthe time that Preston had made a £900,000 bid to buy the striker permanently accroding to reports in the Irish press.
The offer was rejected on the basis that Cardiff wanted to retain the player and so a season long loan was agreed. Doyle has been fairly average for the vast majority of the season failing to nail down a regular spot until recently when injuries to others have allowed him to start up front.
The Bluebirds are curently under a transfer embargo menaing that they are only able to sign players when one departs and even then the incoming player must be on 75% of the wages of the outgoing player.
It is a distinct possibility that Cardiff will be looking to offload some of their playing staff including Doyle to allow them to bring in new blood. After several months of the season it is unclear how keen Grayson will be in renewing his interest to sign Doyle on a permanent basis.