Slattery’s new deal, which will run until 2020, sees him commit his long-term future to a club he has been at since the age of eight.



The 18-year-old midfielder was a regular in the under-23s during the 2016/17 campaign, as well as helping the under-18s to a memorable Youth Cup run which included a victory against Manchester United at Old Trafford.



He also capped off a fine season by helping England under-20s to winning the Toulon tournament, stepping up to take the fourth penalty as the Young Lions ran out 5-3 winners.



Speaking about his new contract, Slattery said: “I’m delighted to sign for such a great club that I’ve been at for a long time now. It’s good to know they’ve got faith in me.



“That’s what this club has always been about as you can see from the past. For me to sign here, it was a massive thing that they give you the opportunities to be in and around the first-team.”



Vice Chairman (Football) Les Reed said: “We’re delighted that Callum has extended his commitment to the football club.



“Callum is a player that is developing well with us, which was shown with his involvement for the under-23s last season.



“He capped off a good campaign by being selected by England for the Toulon Tournament this summer and we’re happy he sees this as the perfect place to continue to work towards his goals.”