He made the decision to switch to outside centre in 2013, with a crowded Scotland back row the chief motivator, and last season made 16 GUINNESS PRO12 appearances in the back line as the Warriors clinched their first title.
Now it looks like a masterstoke, with the 28-year-old heading to the World Cup while back-row teammates such as Rob Harley and Adam Ashe miss out.
"Being picked for the World Cup squad is a real vindication for me and makes me realise I made the right choice but I did doubt things along the way," Vernon told the Daily Mail.
"At the time, I don't know if it was a courageous choice to swap positions as it simply seemed the right one if I wanted to get my rugby career going again.
"I spoke to Gregor Townsend at Glasgow at the time and he encouraged me to give it a go as he knew the difficult situation I was in and how I was frustrated at not getting much game time at the club.
"To be honest, part of the reason I made the change was because at the time Scotland and Glasgow had lots of back rows but were a bit light on centres.
"Then within a few months of me making the change, you had four or five top guys coming through to play in the centre which made me wonder if I had done the right thing.
"I have come a long way since then and everything has been worthwhile. I felt I adapted to the change from back row to centre better than I thought I might do and I've just kicked on. I made a lot of improvements but there is still a lot I can get better at."
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