Late on Monday, two women overheard in a restaurant near the conference centre in Manchester were talking about their day. One, bemoaning the fact that she’d left her glasses in her hotel that morning, said she decided not to go back for them because she didn’t want to "run the gauntlet again".

Her friend sympathised and said someone had thrown a shoe – or rather, a sandal – at her earlier as she joined the queue for George Osborne’s speech.

It was one of the defining features of the Conservative Party conference: the small but baying mob hurling abuse, eggs and apparently anything that came to hand (or foot) as the enemy approached.

Anyone with a blue-ribboned conference pass was "Tory scum", whether they were journalists, sound technicians, lobbyists or indeed delegates and politicians.

Some who tried reasoning with the protesters were spat at through the police cordon. At a rally on Sunday, there were more disturbing scenes of young delegates being hounded by the snarling crowd.

People have the right to demonstrate in our democracy but they also have the right to go about their business unmolested; observing, day after day, the chanters’ faces contorted in fury, I was reminded of a spectacle closer to home.

It was in August last year when the-then Scottish Labour leader Jim Murphy was taking his Irn Bru crate around Scotland to campaign against independence. He had been heckled and jostled before but things took "a sinister turn for the worse", as he put it, in Kirkcaldy.

He was pelted with eggs, jeered by members of the public and accused of being a "traitor", "parasite", "terrorist" and "quisling".

Activists had used social media to make the MP’s visit to Fife "one to remember" and, although on the far fringes of Scottish nationalism, the incident was by no means an isolated one.

The same element reared its head again outside television studios in Glasgow when the BBC’s then political editor Nick Robinson came to Scotland.

Angry marchers branded "Sack Nick the Liar" placards, after the broadcaster committed the crime of asking Alex Salmond a question he didn’t like.

In Scotland, we became accustomed during that campaign to the hate and the name-calling, mostly by cybernats, so when it spilled on to the streets as the September polling day drew closer, we weren’t surprised.

This might not have been the kind of radicalism David Cameron addressed in his speech to conference on Wednesday, when he said he wanted to confront "the shadow of extremism hanging over every single one of us".

He spoke of a more insidious extremism, saying he felt sick when girls were persuaded to leave Britain to become Jihadi brides, and when boys who could do anything they wanted in Britain ended up in the desert wielding knives.

"For too long, we’ve been so frightened of causing offence that we haven’t looked hard enough at what is going on in our communities," he said.

Extremism in any form is alien to the values Britons hold dear and, while the behaviour of a minority in Manchester this week and in Scotland during the referendum may not be as dangerous as Islamic fundamentalism, it also represents an intolerance that has no place in these lands.

In the past, people who had opposing views were able to give voice to their differences without fear of attack. But now, in Scotland and in England, there is a growing band who won’t accept any deviation from their own narrow line.

The election of Jeremy Corbyn – who was described by Mr Cameron as having a "terrorist-sympathising Britain-hating" ideology – has reawakened the hard Left in England and lent it legitimacy.

In Scotland, the Nationalists did the same, recruiting many Labour supporters in the process.

Both Mr Corbyn and the secessionists are credited, not least by themselves, with re-energising the political landscape. The new leader of Labour has talked of his "nicer" and "kinder" politics; last year we kept hearing about the "joyous" Yes Scotland movement.

Well, the Corbynistas didn’t look so cuddly outside the Tory conference, and there was little joy for the opponents of Scottish separatism, who were often too frightened to admit they were Unionists.

Mr Corbyn vowed to "get back to real politics" but that involves discussion with the opposition; the Nationalists claimed they were the colourful and positive camp last year, but there was nothing positive about their harassment of Labour candidates.

Some 60,000 people marched through Manchester on Sunday and most were peaceful. In Scotland, the majority of Yes voters were probably secretly ashamed of their more "colourful" comrades.

Mindless militants have hijacked their parties on both sides of the Border, but there is a big distinction to be made: Labour under Mr Corbyn appears to have absolutely no chance of electoral success, while the Nationalists, for all their rogue elements, continue to win elections, most recently in council ballots (some of which were by-elections triggered by councillors being elected SNP MPs).

Of course, there is the ongoing matter of the constitution in Scotland, though separatism has only lately lured the ultra Left. On top of this, large chunks of the electorate, who might be somewhere in the middle, end up siding with the SNP because they refuse point blank to contemplate the Tories, whatever form they assume.

Not so in England. After Mr Cameron’s appeal to the centre ground at the close of his party’s conference, even commentators on the (moderate) Left were declaring him the new leader of the Left, and the heir to Tony Blair, the former Labour Prime Minister.

One, Dan Hodges, a former Labour Party and trade union official, wrote: "It’s now impossible for anyone on the progressive Left to construct an intellectually coherent argument for voting Labour."

There is a sense that Mr Cameron’s "One Nation" conservatism has touched a nerve not just with his party faithful but with the country. Most, as last May’s General Election showed, would sooner be in the mainstream than on the margins of political debate, and now his house-building, school-reforming, NHS-fixing, social equality agenda is winning over new converts; except in Scotland. This column is not an argument for the Conservative Party but suggests that Scots, too, should start listening to what is being said and forget for a minute who is saying it.

We are the first to defend fairness but the Prime Minister won’t get a fair hearing here, not even with his assault on poverty, his championing of ethnic minorities, and his promise to improve social mobility.

Even if he abandoned all economic prudence and jumped on the anti-austerity bandwagon, Scotland’s anti-austerity movement would still shout him down.

This is not politics; it is prejudice and out of prejudice comes intolerance and extremism. Scotland once had a reputation for rationalism but it hasn’t survived the separatist ascendancy. What else have we lost? Mr Cameron spoke of his love for his country: "I love Britain. I love our history and what we’ve given to the world. I love our get-up-and-go; that whenever we’re down, we’re never out. I love our character; our decency; our sense of humour."

That is what we should hang on to.