The trio put pen-to-paper on their respective deals on Thursday evening — tying them to the club until the end of the 2015-2016 campaign in the process.

Southwell (21) has netted 19 goals in 33 appearances since joining the Pilgrims from Grimsby Town in the summer of 2014, while Mills (22) has been one of United’s standout performers — in a variety of roles — so far this season.

Mills has scored five goals in 38 appearances to date for the Pilgrims.

Roberts (23), meanwhile, has pledged his future to the club too, having made five appearances since arriving from Gainsborough Trinity at the beginning of the New Year.

Reflecting on the triple signing, United boss Dennis Greene told bufc.co.uk: “We are delighted that these three lads have committed their futures to the club.

“It is a signal of our intent to hold down our best players regardless of whether we find ourselves in the Conference or Conference North next season.

“In Dayle’s case in particular, we lost the services of last season’s top scorer for nothing so it was imperative not to let that happen again.”

Greene has, furthermore, agreed a pre-contract agreement with on-loan Spalding United striker Mark Jones — meaning the 25-year-old will re-join the Pilgrims permanently in the summer.

United now have eight players contracted for 2015-2016, with Southwell, Mills and Roberts signed up alongside Sam Vince, Scott Garner, Carl Piergianni, Kaine Felix and Kyle Dixon — with Jones set to follow and make it nine in due course.