The young openside enjoyed a season to remember in 2014 lifting the NatWest Vase with Trent College before being crowned Premiership Academy champions with Northampton.
There was no trophy this season as Saints narrowly lost out to Saracens in the Academy final, but it is with England U18s that Allman grabbed the headlines.
He became an integral part of John Fletcher’s side playing in all six games in a very competitive back-row and he is now looking to add three more caps in South Africa in a few weeks.
“I’m looking forward to the tour. It’ll be a big step up in terms of physicality and interesting to play in an hostile environment too,” he told TRP.
“The past two seasons have been great so I hope I can finish it off in style with an unbeaten tour. It’d be a great way to end my schoolboy career.
“The guys from last year did that so we’ve got a lot to live up to but I’m confident we have the squad to do it.”
Part of a rugby-mad family, his grandfather John captained Sale in the Sixties, Allman started playing rugby at Melbourne RFC aged six and he was soon picked up by Leicester.
He was offered a contract at 16 to join the Tigers academy but it would have meant quitting school so he opted to stay at Trent College for sixth form studies and joined East Midlands rivals Northampton.
Finishing school this week, he will now link up with the Saints Academy full-time as well as enrolling at Loughborough University.
With past and present club teammates Will Owen and highly-rated Saints flanker Lewis Ludlam both too old for England U20s next season, Allman has his eye on their jerseys and the World U20s Championships in Manchester.
He said: “It was tough to turn down that contract at Leicester but I really wanted to get my A-levels before fully committing to rugby. I have no regrets.
“I’ve got pre-season starting with Northampton tomorrow which will keep my mind off the South Africa tour for a while. I’m a bit nervous about what’s in store but I hope it’ll go okay.
“Training with the first team will improve my game massively. The players there will be a lot bigger than me so I’ll have to do things right to keep up.
“I’m not sure how it’ll work next season yet but going to Loughborough and playing for their National League One side could help my rugby develop. Playing men’s rugby will be a big step up as a back- rower so it could be a great steeping stone.
“Getting involved with the Wanderers in the A-League is a big target as well as breaking into the England U20s set-up. Will and Lewis are leaving so if I play well maybe I’ll get in the reckoning.
“If the next two years go as well for me as the previous two, I’ll be over the moon.”