The departure of Allan, who has been capped at all age-grade levels, is another setback for Alan Solomons' side, coming just 24 hours after internationalist Ross Rennie left for Bristol.
While capable of playing on both sides of the scrum, Allan will be an obvious replacement at Glasgow for Moray Low, the tighthead who is off to Exeter next season. Ed Kalman is out of contract this summer and while Mike Cusack is still at the club, his recent injury and illness problems mean there must be some doubt about how much he will be able to play next season.
Edinburgh are not in a much better state. Willem Nel has just about shouldered the tighthead duties on his own this season, playing almost every minute of every game. Though Simon Berghan has been signed to replace Geoff Cross, who is off to London Irish, the New Zealander has been confined to the bench. Alan Dell, a South African, is injured and has yet to arrive, leaving it up to Ewan McQuillin, currently in New Zealand on a McPhail Scholarship, as the only Scottish-born candidate.
For Allan, it was an easy decision to head west. "This is a great move for me," he said. "I'm ready to make the step up and I'm delighted to have signed a professional contract with the Warriors. I really enjoyed working with Shade [Munro] and Kenny [Murray] when I was part of the Scotland A squad earlier this year and I'm looking forward to working with them again, along with the other coaches at Scotstoun."