It recalled the BBC director general, George Entwistle, being jeered by MPs over the Newsnight/Savile affair.

John Swinney, the Scottish Finance Secretary, was ridiculed by the House of Lords economic committee on Tuesday for trying to argue that an independent Scotland would be able to remain in the EU because it would still be part of the UK when the negotiations took place. The "last refuge of the scoundrel" sneered one Peer. "Doesn't know what he's talking about," said another.

Their lordships' eyes rolled to the ceiling in mock amazement as a diffident Mr Swinney tried to argue that the President of the European Commission, Jose Manuel Barroso, had not said what he clearly had said in a letter to the committee. Namely, that after independence Scotland would become "a third country with respect to the EU" and that the various treaties "would no longer apply on its territory" and that the new entity would have to apply for membership "like any other state". The chairman, Lord McGregor, treated Mr Swinney as if he were a rather dim sixth former at a minor public school.

It wasn't really Mr Swinney's fault – the constitution and Europe aren't his brief after all. They are Nicola Sturgeon's. And the patronising peers, such as Lord Forsyth and Lord Lipsey, are of course political appointees and hardly independent authorities. Mr Swinney had been left dangerously exposed by his own party, which has tried to ignore this issue for far too long expecting it will go away. This won't do. You can't be the party of independence in Europe when the top guy in Europe is suggesting Scotland would be ejected from it.

Ms Sturgeon has been dragged kicking and screaming to give a statement on EU membership to Holyrood today, just as Alex Salmond was dragged to the chamber to explain the non-existent legal advice in October. This is undignified. No doubt she will insist the Barroso Barrier doesn't exist and he's just kidding, ha ha. But he isn't. Mr Barroso has chosen to get involved in this issue for his own political motives. Bureaucrats, like cushions, tend to show the imprint of the last person who sat on them. Mr Barroso is under pressure from other member states, such as Spain, who have their own separatist movements, not to say anything that might encourage secession.

The SNP should have challenged him on the membership issue back in September, when he first started comparing Scotland to a "new state" that would have to reapply. Scottish Government sources dismissed this at the time saying he didn't mean Scotland. Then Mr Salmond deployed tortuous constitutional logic to argue that, because the Scottish independence referendum is legal and because, under the Edinburgh Agreement, the UK Government has agreed to recognise the result, Scotland would remain a "succession state" and that EU treaties would still apply. Unfortunately, Mr Barroso does not agree.

Mr Salmond and Ms Sturgeon should there and then have booked a ticket on Ryanair and jetted across to the European Commission. They should have held a press conference to ask the president if he was seriously suggesting that, if Scotland were to become independent as the result of a legitimate democratic referendum, he would authorise the expulsion of 5.2 million EU citizens from the European Union. Could he explain the mechanism by which Scotland could be ejected, since there is no treaty covering such an eventuality. Since Scotland has been subject to European law now for 40 years how could those protections be removed by the whim of the Brussels Commission? In other words: no way Jose.

But the SNP doesn't seem to realise how serious this is, or perhaps it is the arrogance of power. All long-serving governments have a tendency to listen only to people who agree with them. The Scottish Government insists that, in the end, Brussels will see reason. Certainly, the idea that Scotland would actually be forced to leave the EU is so absurd that not even the SNP's most vehement critics, like Labour's Lord McFall, argue it. But it's no use just asserting this, or endlessly citing the views of sympathetic professors – the matter should have been addressed politically.

Mr Barroso is worried that, if he appears to endorse Scottish independence, he would be attacked by Tory ministers in Westminster for encouraging the break-up of Britain. And he's probably right. Imagine if the Commission president had said "we would welcome an independent Scotland as the 28th member of the European Union". Tory MPs would have been apoplectic at this latest Brussels conspiracy against Britain. The elephant in the room here is that David Cameron is already under intense pressure from figures like London Mayor Boris Johnson to hold a referendum on British membership of the EU after the next election. Indeed, it's not inconceivable that Scotland could be negotiating entry to the EU at the very moment England is negotiating its exit – which would be interesting.

The SNP has to reframe the entire argument. It has anyway been too uncritical of Europe, which is plunging half the eurozone into economic depression through inflexible application of monetary policy. By appearing to be humble supplicants at the EU tradesman's entrance, the SNP is only weakening its own bargaining position if Scotland votes Yes. Oil-rich Norway does pretty well outside the EU. The line should be that the dysfunctional European club would be lucky to have such a highly educated and prosperous country as Scotland with its oil and natural resources. I mean, where would Spain get its fish?

The correct way for the Commission to deal with a situation unprecedented in the EU treaties is surely to say that the status quo should be affirmed, ie that Scotland is in until it is out. Scotland would clearly have to negotiate its contribution to the EU budget, its relationship to treaties such as Shengen and its posture on the single currency. But the other new entity, the "Rest of the UK", would also have to conduct its own parallel negotiations on altering its contribution to the budget, and as a much-reduced country, its voting weight on the Council of Ministers. That's if England wants to stay in the EU.

As for Mr Barroso. It is time for Mr Salmond to park his ample derriere very firmly on the Brussels upholstery.