Glenn had refused offers to leave Scotland believing he would be offered a new deal to remain with Glasgow, however, when his salary was cut by more than 50 per cent he engaged former Glasgow team-mate Shaun Longstaff, now an Irish-based agent, who came up with opportunities in France.
Ironically, Glasgow returned with an offer which would have been good enough to keep him, but by then Glenn had already committed himself to a move.
"It has all been a bit complicated," Glenn told The Scotsman. "I would have loved to finish my career at Glasgow and thought I would, but when Glasgow made it clear they weren't too bothered about keeping me, I was contacted initially by Bayonne and was happy to go there. But their offer wasn't what I was led to expect - it would have caused me and my family a bit of hardship to be honest.
"I was keen to go to France for the experience, and being a retired international I wasn't looking for great wages, but then Shaun found Castres Olympique were interested. Glasgow coming back with an offer complicated it again because if I'd been offered that at the start I'd have stayed, but I'd already committed myself to going and I'm now looking forward, to a fresh challenge in France."
Glenn has signed for six months initially as injury cover for talented young back Roman Teulet, but he is hopeful good displays will earn an extension to the end of the season.
Stuarts's career has taken as complicated a turn, but for the better since Longstaff also took up his case. Stuart, who joined Glasgow two years ago, was told he wasn't wanted at the end of the season despite having a year of his contract remaining. Stunned and disillusioned, the three-times capped full-back was still contemplating quitting rugby altogether when he was called up as a replacement for the injured Chris Paterson on Scotland’s tour in Australia last month. He starts afresh today with the Borders.
Glasgow are now left with a shortage of full-backs and back-three experience, but strangely, with two international full-backs on their books, the club decided they were surplus to their requirements.