It was a full 19 hours later that the Scotland manager Dougie Morgan called back to say he was in.
"It was a long wait but an incredible feeling when he did call," Mather said. "My mind had gone every way - I was in, I was out - and I couldn't sleep at all.
"I kept going and checking Teletext to see if they had made a decision and someone else had been called up, thinking at least I'd know and I could finally get to sleep. I can't say I'm looking forward to the 30-hour journey, but it feels like heading for a pot of gold at the end of the rainbow."
"As soon as Dougie Morgan (Scotland's manager) hung up the phone, Phil Davies (Leeds' director of rugby) was the first person I called, even before my dad," said Cammy as he prepared to fly out to Australia.
Phil Davies took Leeds to the English Premiership where Cammy won the players' and supporters' player of the year awards.
"I'm a realist, I'm going out there as sixth-choice back rower, and by the time I come into contention we'll have the two most important games in the pool to come so I might not see any game-time. But I'm a lot closer to playing for Scotland in Australia than I am sitting in Glasgow, and at least it shows they're interested in me again."