Will Grigg transfer fee causes much debate - here's what we know about Sunderland's League One record swoop

The Black Cats announced this morning that the transfer had gone through after they filed the appropriate paperwork before last night's 11pm deadline.

Sunderland and Wigan announced the signing together, but while the Black Cats didn't mention a fee, the Latics called it a £4m transfer.

There's been much conjecture over the fee for Grigg, which is a League One record.

Depending on who you believe, Sunderland have had anything from four to seven bids rejected before finally landing their man.

Reports suggested that they started their bidding at £250,000 earlier in the window before finally stumping up a figure that could rise to £4million. That much has been confirmed by Sunderland owner Stewart Donald.

How is that structured remains the talking point. Guaranteed payments of £2million with the rest in add-ons have been suggested at the SAFC end, while respected Wigan journalist Paul Kendrick, who spent all day yesterday behind the scenes at the club, says it is £3.25m down payment and £750k in add-ons.

Donald himself insisted that Sunderland haven't overpaid for the Northern Ireland international.

He tweeted: "I hope it gets to £4M as that would mean we are playing football in the Premier League."

From the Wigan end, Kendrick claimed that in a mad half-hour last night, the fee for Grigg escalated from £1.5million to £4million (including add-ons) which was eventually enough to persuade the Latics to sell.

Wigan boss Paul Cook confirmed: “The club desperately wanted to keep Will but this is an offer we simply couldn’t refuse.

Either way, there's no doubt that Sunderland have ended up paying more than they wanted, given the lateness of the deal. Grigg's signing is a record for a third-tier club, however it is structured. But it will all be worth it should he fire the club to promotion.