It is planned that in the event of a No vote in the September referendum the three parties will quickly open formal talks about a common position on additional powers for the Scottish Parliament, particularly on taxation.
In a bid to counter claims by the Nationalists that the pro-UK parties are not serious about devolving more powers, the senior coalition source has also said that there is now “a growing consensus” that the first Queen’s Speech after the general election in May next year will contain a bill to devolve more powers to Scotland, whichever party wins.
Last month, Labour leader Ed Miliband confirmed that his party would pledge to bring in a new Scotland Bill in his first Queen’s Speech if elected prime minister.
The Scotsman has been told the Lib Dems, who still hope to be the power brokers after the 2015 election, will make the same promise and it is expected that the Tories will follow suit.
The party leaders in Scotland – Johann Lamont for Labour, Ruth Davidson for the Conservatives and Willie Rennie for the Lib Dems – have held talks leading to their declaration in May that they would push through new powers.
The senior government source conceded that the start of an election campaign may delay reaching an agreement on devolution because “we will be spending more time highlighting our differences by then”. But he added: “I am sure we can all reach an agreement.”
But a spokeswoman for Deputy First Minister Nicola Sturgeon said: “The Westminster parties have had numerous opportunities to deliver on their promises and repeatedly failed to do so.”