In an interview with the Sunday Herald, David Martin, Labour MEP for Scotland, effectively distanced himself from claims by the Better Together campaign - which he supports - that Scotland might fail to become a member of the EU after independence or be rejected by the European Commission.
He also said that Scotland will not have to join the euro or the Schengen common travel area in the event of a Yes vote. "My view is that Scotland, of course, would get into the EU eventually," he said. "It's not automatic, and would take several rounds of negotiations, but they're not going to force us to join Schengen. They're not going to force us to join the euro."
Martin's views carry considerable weight. First elected in 1984, he is Britain's most senior Labour MEP, and indeed the second-longest serving member of the entire European Parliament.
He made clear that he is campaigning for a No vote in September's referendum, and does not wish Scotland to break away from the UK. But he indicated that he expects the European Commission to be much more flexible in the event of a Yes vote than it has suggested so far.
The No campaign has made much of the view expressed by Jose Manuel Barroso, the president of the commission, that Scotland's membership would be "extremely difficult if not impossible". But Martin said: "There would be negotiations, and I think the commission would recommend Scotland qualifies for membership. Formally the commission say they can only talk to the government, and until a government is elected we can't negotiate. But they're not going to wait till March 2016 [the proposed date of independence] to start negotiations, so informally there would be discussions - and I don't think it matters whether it's formal or informal."
His comments were welcomed by Yes Scotland. Chief executive Blair Jenkins said: "What David Martin is saying demolishes core elements of the No campaign's claims about Scotland's EU membership and confirms what a host of experts, and most sensible people, have been saying since the independence campaign began. After a Yes vote, Scotland will be a welcome, valuable and valued member of the EU and crucially, as Mr Martin underlines, will not be forced to join Schengen or adopt the euro."
A Better Together spokesman said: "Nobody is arguing that we wouldn't get into the EU if we left the UK. What nobody can know is how long that process of re-admission would take and what conditions would be attached."
Martin said the main question mark about Scotland's entry into the EU was the timing, describing the 18-month timetable envisaged by the Scottish Government as nonsensical. He suggested the best option would be to lengthen the timetable, as 18 months was not realistic either for the talks with Westminster or with Brussels.
However, he said talks on Scotland's EU membership could begin, at least informally, soon after a Yes vote, and if they were not completed before independence day temporary solutions could be found to smooth the transition.
Under the Lisbon Treaty, Scotland's quota of MEPs would rise - if it became independent - from the current six to 11 or 12. Though this would be good for Scotland, Martin said it could also slow down the negotiating process as it meant five or six other countries would have to lose an MEP each, and they would not do this lightly. But Martin's Liberal Democrat opponent, George Lyon, said he could not envisage a situation where the other 28 states would grant any exemptions - on Schengen, the euro or the budget rebate - to a new applicant such as Scotland.
The Conservatives' top candidate in Scotland, Ian Duncan, declined to be interviewed on the subject, while Ukip's David Coburn said that, in the event of a Yes vote, he "would be negotiating for us to rejoin the UK, not join the EU".
For the SNP, Ian Hudghton said he expected the UK Government to help an independent Scotland negotiate its continuing membership of the EU.