The 23-year-old was a virtual ever-present for the Seagulls last term, and completed a £50 million move to Arsenal last week.
But Albion coach Graham Potter is seemingly unflustered about losing the England international.
Speaking recently, he said: “I think we have got enough competition in that area. We have got enough good players. We can be flexible with how we set up.
“You can’t replace a £50 million player, you have to look to be creative with solutions within the squad. But we are in a good place now.
“We wish Ben well, he has been fantastic. His journey from the academy to Newport County, to Peterborough, to Leeds United is fantastic for him. To then get a move to Arsenal is a great achievement for him and the club.
“It is a proud moment for everyone connected with the club and I am really pleased for Ben. The fee gives us a fantastic opportunity to develop the club and progress the team."
Potter was speaking after Albion’s first win of pre-season, a 3-1 victory against Luton Town at Kenilworth Road where goals from Aaron Connolly, Enock Mwepu and Percy Tau sealed a 3-1 win.
“I thought we played well in the first half especially; we controlled the game, created some good chances and scored some good goals. I was really pleased for Enock [Mwepu] to get off the mark.”
We’ve gathered the best of today’s Premier League speculation below...