Jack McConnell, Annabel Goldie and Nicol Stephen.
If there were an election tomorrow the Lib Dems could see a swath of their North seats go to the SNP. A lot of grass routes Lib Dems weren't that happy with coalition with Labour in power, they're seething over this apparent 'coalition' in opposition with Jack McConnell and the same goes for a good chunk of those who voted Lib Dem in this part of the world too.
Plus after the shambles of May's election for the opposition parties to be seen to deny the people a vote on this can only damage themselves and not the SNP.
Why Jack McConnell, Annabel Goldie and esp. Nicol Stephen continue to flog this I don't know, because the further they go with it the more foolish they will look. There are people on the Opposition benches that would vote YES in a referendum, there are plenty more including arch-Unionists who given a free vote would back the Referendum Bill.
They argue uncertainty is bad, there's one way to deal with that, hold a referendum, if the opposition are right then the Union will be secured for a generation, if they are wrong then the will of the people will have prevailed. By all means oppose Independence, but opposing the referendum is and will increasingly be seen to be indefensible.