At 31, Gray - who trained with the squad earlier this week – is an experienced professional who won the last of his eight caps against England in last year's championship.

Edinburgh's uncapped scrum-half, Greig Laidlaw, was also called in to the squad but has so far been unable to join in training due to a shoulder knock.

There is good news on the injury front with team doctor James Robson revealing flanker Alasdair Strokosch is stepping up his rehabilitation following an ankle injury, while Edinburgh scrum-half Mike Blair is making similar progress after an ankle injury.

But flanker Ross Rennie missed training on Tuesday as the Scotland medical staff assess the knee injury he sustained during Edinburgh’s Heineken Cup victory over Stade Francais at the weekend

Uncapped Edinburgh back Jim Thompson also missed training due to a swollen knee while 20-year-old Glasgow lock Richie Gray, who was called in to the squad this week, is currently on the sidelines nursing a facial injury.