Gordon Wilson said the party should start laying the groundwork for another poll now, following Ms Sturgeon’s revelation she will shortly set out the circumstances that could trigger a second vote.
However, he said the forthcoming in/out referendum on the UK’s membership of the EU, widely touted by senior SNP politicians as the most pressing possible trigger, should not be used as a pretext for another vote.
Mr Wilson said there is “a delusion amongst (SNP) leadership Europhiles that SNP members, never mind Yes voters, will back Scotland staying in the EU”.
He also said a referendum predicated on Westminster’s expected renewal of the UK’s nuclear weapons “would only cement a No vote” as Scotland is “split down the middle on Trident”.
However, he recognised Ms Sturgeon faces a dilemma in simmering the “seething cauldron of support for another referendum on independence” among the SNP’s tens-of-thousands of new members, with more temperate heads calling for a cautious approach.
Blair Jenkins, director of the failed Yes Scotland campaign, predicted there will be another referendum “although probably not before 2021”, urging his nationalist successors to work towards as big a majority as possible over a long period of time.
Mr Wilson said: “Nicola Sturgeon has pre-empted much of the pressure yet many Yes supporters do not look ahead.
“They see only the driving need for independence and their call for an immediate second effort is blind to the hazards.
“Nicola Sturgeon is correct when she links it to the prospects of victory. That is the only trigger factor.
“Scotland is split down the middle on Trident, so that would only cement a No vote.
“Behind the siren calls for independence in the event of Scotland voting to stay in Europe while England decides to leave, there is a very real danger. It is an iceberg lying in the track of an approaching indyref2.
“Firstly, it would come too early. There has been little or no change in the levels of support for independence from last year. The polls show support oscillating between 43% and 52%.
“The economic arguments torpedoing last year’s attempt remain. The spadework still has to be done and the electorate persuaded.
“Also, the over-65 generation - mine - happily have not yet died off and they will still be looking for pension security.”
He added: “Many nationalists cannot be relied on to vote for independence in Europe. They have seen how small countries like Cyprus and Greece have been bullied and how Ireland was forced to hold a second plebiscite until the vote suited the Commission.
“Under no circumstances should the European referendum result be a trigger for an independence referendum, unless and until sophisticated and up-to-date attitude surveys demonstrate the certainty of victory.”
Now that the SNP is committing itself to a new referendum, “the party owes it to the people to prepare for the day”, he said.
“She should appoint a party campaign director now. We cannot afford a re-run of 2014. Proper preparation will make all the difference.”