Billy Gilmour has completed a move from Albion to Napoli.

He has joined the Serie A giants on a five-year contract for an initial fee of £12 million, potentially rising to £16 million with add-ons.

Albion turned down an offer of £8 million from the same club earlier in the summer.

The news will disappoint many Seagulls fans and completes what has been a changing of the midfield guard this summer.

Albion also lost the services of Pascal Gross and attacking midfielder Adam Lallana but have invested strongly in Mats Wieffer and Matt O’Riley as well as seeing Yasin Ayari impress on his return from loan.

They will look for Carlos Baleba to continue to progress in his second season in the Premier League.

Head coach Fabian Huerzeler has also made it clear he will use James Milner as a midfielder while Malick Yalcouye has been brought in with a view to the longer term in that area of the pitch.

The arrival of Diego Gomez from Inter Miami will be confirmed in the January window.

Announcing Gilmour’s departure an hour before the transfer deadline, Albion wished him ‘good luck’ in Italian and tweeted: “Thanks for the memories, Billy!”

Gilmour arrived in a deadline night deal two years ago, with Albion paying Chelsea about £9 million.

He really came to the fore last season after the club sold Moises Caicedo and Alexis Mac Allister.

Technical director David Weir said: “Billy quickly established himself as a popular figure in the dressing room and was a key player last season when we competed in the Europa League for the first time.

“We wish him the best of luck with this move to Italy and thank him for his efforts with the club.”

Having missed this summer’s public pre-season friendlies, Gilmour did an effective job late on in the 3-0 win at Everton, then started at home to Manchester United and produced one of his finest performances for the club.

Fans rose to applaud him when he was replaced near the end, aware it might be his farewell.

Huerzeler said: “I have thoroughly enjoyed the short time I worked with Billy. He’s a great professional and I wish him all the best for the future.”