“If we can’t get the organ grinder then we have to consider the monkey.”

Alex Salmond has opened secret talks about appearing in a TV debate with Alistair Darling in the weeks leading up to the referendum.

The First Minister yesterday called for David Cameron to go head-to-head with him on live showdown. But The Sunday Post understands Mr Salmond has privately signaled to broadcasters he is willing to take part in a debate with the leader of the Better Together campaign.

The SNP leader has previously insisted he would only debate with senior figures in the No campaign on the condition that the Prime Minister first agrees, which the Prime Minister has steadfastly refused to do.

A source close to negotiations in the Yes camp said: “If we can’t get the organ grinder then we have to consider the monkey.”

Any deal on a Darling versus Salmond showdown will take months to agree and it is thought the debate, or series of debates, is more likely to take place with a commercial broadcaster than the BBC.