The towering lock might have retained his soft, youthful features, but he has been playing some very grown-up rugby lately.
The abrasive edge Gilchrist has added to his game has brought him four Scotland caps, and it no doubt added a healthy wedge to the new contract he has just signed with Edinburgh to keep him in the capital until 2016, but its completion is as much an expression of his confidence in them as their faith in him.
"I had no real reason to leave," Gilchrist said. "We are moving in a great direction and my role has developed. A couple [of other clubs] had been in touch, but I didn't go out looking for anything. People were made aware pretty early on that I was happy to stay."
Gilchrist's decision follows Dave Denton doing likewise last week. And for similar reasons. He is still in his infancy as a top-flight forward, and he feels he can add a polish to his game in Scotland that might be harder to acquire elsewhere.
"I have a lot to learn still," Gilchrist added. "I've been lucky to get four caps so far, but my goal over the next couple of years is to push on. That will come from my performances with Edinburgh."
Today, however, his focus is on the annual domestic dispute that is the 1872 Cup clash with Glasgow. Gilchrist has yet to taste victory over his mates from the other end of the M8. And as genial as he may be in most things, he does not disguise his distaste for defeat. "It's horrible," he added, with a shudder. "It's not a place you ever want to be.
"Glasgow have maybe lost a couple of games, but they had a good start to the season and are going well in the league," he said. "We have been improving slowly. It was always going to be tough with Alan [Solomons] coming in at the start of the season and changing a lot of things, but we feel we are on the up. Guys are getting confidence and the back-to-back wins have shown a different side to Edinburgh.
"We have been gritty and defended well - things that the team and individuals have been criticised for in the past. That's pretty satisfying but is something that can be taken away in one bad performance. If we play badly against Glasgow then what we did before is just a flash in the pan. But if we keep building and improving then we can start going places."
Given his decision to stay, it is perhaps an ironic choice of words. But no less true for that.