One of the many benefits in being a superannuated politician is that people forget.

After a time, they stop asking what it was that made you so distinguished. While they attend to your sage advice, they neglect to recall what it was you did or failed to do when a bit of sagacity might have been useful.

Nigel Lawson, Baron Lawson of Blaby, has made a whole second career out of telling the young pups of politics what's what. Because deference makes their world go round, the whelps never say: "Hold on. Weren't you the Chancellor who gave us 15% interest rates after a contrived boom that ended in one of the biggest busts this country has seen?"

While he makes sonorous noises on budgetary rectitude, few ask about the Chancellor who set sterling on a suicidal game of tag with the old Deutsche mark. When the grand old man says Britain must leave the European Union forthwith, no-one on Radio 4 wonders why he made such a fuss, all those years ago, about the need for Britain to join the European Exchange Rate Mechanism.

Now Lord Lawson wants us "out". He is taking a lead part in the Tory chorus that says no harm will come of being in a country detached from the EU. The former Chancellor, who also has fascinating views on climate change, says that Britain will be better off in splendid isolation. He is as reliable as he ever was, then, when he asked the rest of us to bet the house on his interest rate policy.

Establishing just why Lord Lawson thinks we'd profit from leaving the EU is a little tricky. In a newspaper article, he tosses around a few numbers describing trade flows. He doesn't say why trade with anyone, anywhere, is hampered by union membership. He does say, however, that quitting Europe would preserve the City of London from a "frenzy of regulatory activism". He means a financial transactions tax.

So the baron speaks up on behalf of the banks and calls it an argument in the national interest. That sounds like the Lawson of old. It sounds like the Tories of old, too, when the obsession with Europe and sheer panic over Ukip combine to turn ancient prejudice into policy for still another generation.

David Cameron tried to feed his sceptical benches with a little undercooked meat in the half- promise of an "in-out" referendum. Predictably, they chewed that up and spat it out. Lord Lawson now peppers the leftovers with some grandee balderdash to assert – Nationalists, pay attention – that quitting a political and economic union is simple, painless and without consequences.

Without being parochial, you might want to wonder why what works for Britain, in Lord Lawson's world, couldn't work in parallel for Scotland. In honesty, you might then say that if the former Chancellor is wrong about a European Union, how could a Nationalist be right about a British Union?

One answer is simple. No-one suggests an independent Scotland would float off, economically, into the North Atlantic. Another answer has to do with Lord Lawson's presumptuous language. He writes: "Not only do our interests increasingly differ from those of the eurozone members but, while never 'at the heart of Europe', we are now becoming increasingly marginalised as we are doomed to being consistently outvoted by the eurozone bloc."

To which the pragmatic, self-interested and entirely political response comes: Who's this "we"?

Lord Lawson did not trouble himself to wonder what the entity he understands as Europe might mean to all the bits of the place he comprehends as Britain. He worries first and last about the City of London, not about the backwaters where the rest live. He is intervening in the argument in the hope of forcing a Tory choice for the benefit of his kind of Tory.

Nevertheless, thanks to Ukip, Mr Cameron's backbenchers and the tabloids delight in xenophobia, Lord Lawson could get his heart's desire. With Nigel Farage as their back-seat driver, the Tories could soon be steering Britain, and Scotland with it, out of Europe. They would win a referendum, I have no doubt, fair and square. Should we, those living and working within the borders of Scotland, accede to such a thing?

The question sets a lot of arguments on their heads. George Osborne has told us what his Treasury might and might not accept in negotiations with an independent Scotland. We hear a lot about what a rump UK could or could not accept in terms of debt or defence.

What happens if Lord Lawson and his like get their way and decree that euroscepticism rules?

As it happens, I'm not one to make much of a distinction between our vaunted cosmopolitan Scotland and europhobic England. The polling is scarce and mostly trivial. My feeling – no better than a feeling – is that Scots are slightly less spooked by "foreign" than our friends to the south, but that's probably the company I keep. The important issue has to do with choices and who is allowed to make them.

Lord Lawson is marvellously blase about a huge decision. If it's good for the City, it's good enough for him. That might not cut it for the rest of us. A few Tory cabals and some grumbling in the Shires could detach Scotland from a historic project. The question is not whether you love or despise the EU, but whether you accept the idea that decisions can be made in this way, by these people, for these reasons.

You could be Welsh, Irish or Cornish and have the same wonderment at languid Baron Lawson's sense of entitlement. Scotland has its head above the parapet, however. Our stake in Europe is not insignificant. Our historic ties with the continent – would the former Chancellor even have heard of those? – are very old.

For Lord Lawson, it doesn't matter. A country that struggles to return a single Conservative MP is to be at the disposal of the City thanks to an incoherent argument within the Tory family. Doesn't sound like much of a plan, chaps.