The former MP insisted that “ignoring the chance to develop and publicise a plan B argument was a serious error” from the pro-independence campaign.
Both the Scottish Government and the then first minister Alex Salmond made clear their preferred option was for Scotland to retain the pound after independence, in a “currency union” with the rest of the UK.
But this plan was firmly ruled out by Conservative Chancellor George Osborne and his Labour and Liberal Democrat counterparts, allowing those campaigning for Scotland to stay in the UK to argue it was unclear what currency the country would use if there was a Yes vote.
In a new book to be published on September 18 - exactly one year on from the referendum which saw Scots reject independence - Mr Sillars described the plan for a currency union as a “gift to the No side”.
Extracts from Mr Sillars’ book In Place Of Failure: Making It Yes Next Time ... Soon were published in the Sunday Times.
In these the former SNP deputy leader said: “I got in touch with some members of the Yes Scotland advisory board to persuade them that, whatever the SNP government said about a currency union, the broader Yes campaign had to have a plan B: our own Scottish currency.
“Most of them agreed and at one meeting of the advisory board a majority wanted an alternative plan.
“This fact has never been made public, primarily because that majority was persuaded that to declare for a plan B would be seen as the Yes side being split.”
Former Labour MP Dennis Canavan, who was the chair of the Yes Scotland advisory board and another of its members, Patrick Harvie, the co-convener of the Scottish Greens, both made clear they supported a new Scottish currency in the event of a yes vote.
Mr Sillars, who was not a member of the advisory board, said that “throughout the campaign, and as a big contributor to uncertainty, the proposal of a currency union was a gift to the No side”.
He said the the issue of currency had been “at the heart of the independence referendum” and added: “The only conclusion we can reach from that scarring experience is that there can be no more talk of currency union.
“The independence movement must opt for the most obvious and sensible alternative: our own currency.”