The chief secretary to the treasury delivered a stark warning in Westminster, saying independence could have “a huge effect on mortgages and businesses”.
Alexander said: “In the event of a default, or a refusal to accept debt, one bank, Jefferies investment bank, has done the only detailed estimate out there. They have suggested that under those circumstances there would be a premium of more like five percentage points in that default scenario.
"Assuming a 75% pass through from bond rates to mortgage rates, that would be an extra cost of about £5,200 on an average mortgage cost in Scotland."
McGrail listed this as just one more problem Scotland faces should they vote for independence.
He said: “When people start hearing about potential mortgage potential increases that’s going to get a lot of people saying no.
“It’s that leap into the unknown.”
He felt that the politicians in Westminster were not bluffing when talking of Scotland losing the pound.
McGrail added: “As Danny Alexander said last night this is not a threat, it’s real. You can’t leave and take a share of the pound.”
He accused Scottish National Party leader Alex Salmond of having few specific policy ideas to tackle these challenges.
He said: “I don’t think we have enough detail – I don’t know why he’s assuming that wouldn’t be a problem. It’s too idealistic.
“The fact that he thinks they could walk away from countries and keep the pound is interesting.”
FirstMortgage is based in Edinburgh, Dundee, Falkirk, Aberdeen and Glasgow.