"I HIT bottom. But then I heard somebody tapping from underneath." It’s a Polish saying. But it’s immigrated to Britain. Each time, you think there’s nothing worse they can do. And each time another even grosser blunder arrives to splinter away more of the world’s diminishing respect for the United Kingdom. And here once more comes the English political elite, treating their subjects as credulous peasants, and getting away with it.

Can something even more humiliating than absurd Brexit and its dishonoured referendum be waiting round the corner for its cue? Surely there’s no further to fall, after Tory ministers threaten to use nearly two million foreigners living in Britain as diplomatic hostages? Just listen for the tapping underneath.

I remember the sound of three mighty London demonstrations against misrule, separated by a tract of 60 years. First memory is the battering of hooves and the screams of women, drowning the chants of "Law, not War". That was the Suez protest in November 1956. That was the end of political virginity for my generation. We had never imagined that a British government could commit criminal, illegal aggression in a secret conspiracy with France and Israel to invade Egypt, overthrow its regime and return the Suez Canal to private shareholders. We did not know, until then, that "our" police could slash batons across the faces of young girls, and drag them across the pavement by the hair.

An innocence died. So did a hank of the nerves which had told the British public to obey orders and – with mild scepticism – to trust those who gave the orders. But the Establishment (which wasn’t yet called that) was surprised and vexed at the fuss.

Anthony Eden, the prime minister, had sent a junior minister down to Eton at the height of the crisis, to persuade the teachers there not to sign a protest letter to The Times. But they decided not to sign after all, so everything was all right really. And a year later, the British re-elected a Tory government.

But, out of sight, Suez shrivelled Britain’s once-dominant political influence in the Arab region to that of a pricey weapons dealer. Out of sight, many Brits began to worry that their country was no longer the world power it still pretended to be. And their guarded but affectionate attitude towards the United States began to ferment in unhealthy ways.

President Eisenhower was appalled by the Suez adventure. He brought it to a screeching halt by simply turning off the money: the pound free-fell until Eden gave up and stopped his troops. It wasn’t the first time America had pushed a London government into changing policy. But now a weakened Britain became dependent on America for its own parade uniform. Metaphorical sashes and epaulettes suggested that the United Kingdom was still a Victor Power of the last war, one of the big four at the top table with its own sector in divided Berlin and a permanent seat on the Security Council. The brightest sash was provided by a new "independent nuclear deterrent", which was – is – in reality American in maintenance and targeting, "intelligence co-operation’"with the Americans remains one of the holiest elements of the "special relationship". But what it’s really worth we have no means of knowing.

The sound of my second demonstration is the sound of 100 earnest conversations over the squeak of buggy wheels. In 2003, people came out onto the streets family by shocked family, university departments with off-duty hospital staff, school common rooms with hard-metal bands, to shout that the Iraq war was "not in our name". They say that there were a million of us, something never seen before or since.

We didn’t stop the war. But last week Chilcot confirmed quietly what we had assumed 13 years ago: that we had been systematically deceived, that the case for invasion had been confected, that the lack of post-conflict planning was utterly criminal.

But the episode I found most agonising doesn’t seem to occur in Chilcot. This was the message – never meant to be revealed – sent by Donald Rumsfeld to the British government at a moment when Tony Blair seemed to be in bad trouble with the House of Commons. Rumsfeld said that the British soldiers didn’t really have to fight and take casualties. Instead, they could do safe things like looking after prisoners of war or supervising reconstruction. But of course they did fight and 179 of them did die. So why? If the American generals saw no real need for them to do combat stuff … why did they do it?

The answers hurt. Because their rulers had to maintain the pretence that the Brits were there for a task which could not be done without them. Because the world despises troops on a battlefield who have guns but don’t use them (like the Dutch soldiers who failed to protect Bosnian civilians at Srebrenica). Because Tony Blair wanted to keep up the pantomime of British independent grandeur, the pose of a proud and equal ally of the United States. "I will be with you whatever." Doing whatever? Clearing rubble?

And this: "Our ambition is big: to construct a global agenda around which we can unite the world." Note the word "our": Tony and George will unite the world together. Note the word "big" – an understatement for a programme so gigantic that even Hitler or Stalin didn’t quite proclaim it. But Tony Blair, no fool, isn’t seriously dreaming of global conquest. No, he is deliberately playing down to George Bush. He is trying to hit what he imagines is the right note of vast can-do optimism the Americans seem to fancy.

Chilcot says that the consequences of the Iraq invasion continue into our own time. One of them has been to darken British views of the United States – in two ways. The public has not forgiven the arrogance and ignorance of George Bush and his "New American Century" cheerleaders. Guantanamo and "rendition" have been understood not only as blatant illegalities but as insults to British sovereignty through the abuse of UK citizens with the craven collaboration of British intelligence services. And the Establishment, already scarred by American "interference" at Suez, has developed a septic mixture of obsequiousness and resentment towards Washington. The Wikileaks papers revealed that the US Embassy in London is all too aware of this. Politely, they endure British politicians who try to enlist America in their domestic squabbles while privately sneering at American "interference".

But another outcome of Iraq was to wash away more of Britain’s diminishing trust in its own rulers. As late as the 1980s, it was still true that British and Scandinavian publics – in contrast to most other European nations – broadly respected their political class and assumed that its members were mostly honest rather than corrupt. Twenty years later, that difference had faded. The reign of spin and social dismantling, which provoked such disgust over the war and such disillusion with Blair’s "New Labour", left the British feeling abandoned, betrayed and powerless.

But here the island began to divide. When Scots felt like "taking back control" of their country, or escaping from distant unelected lawgivers, they had somewhere to go. They turned to the practicalities of devolution or independence. But the English had nowhere to go. All over Europe, east and west, the earthquake of free-market economic change had created armies of losers, insecure millions deserted by the social-democratic parties whose mission used to be to defend them. England was no different. The trauma of Iraq and the disappointment with New Labour combined into a formless rage. Who was to blame? The politicians, up there out of reach, in it for themselves. The immigrants swarming in and getting housing priority and living off our benefits. Faceless bureaucrats in Brussels.

This is where the great English tragedy of Brexit began. The fox saw the hounds coming, and directed them to a passing hare. A section of the Conservative Party, encouraged by Ukip successes, saw that popular consent to the whole UK power structure was dissolving in this flood of disgust. So they channelled it, away from their own doors and towards the myth that "outsiders" in Britain or Brussels were to blame for austerity and public squalor.

How did they get away with it? How could millions of fair-minded people who had been able to see through the manipulations of 2003 let themselves be misled in 2016? The Leave caravan shamelessly made its case up as it went along. It was frivolous, and yet it pushed the serious reasoners into the ditch.

But there is a thread connecting English moods over Iraq 2003 and Europe 2016. It is insularity. The least successful Leave slogan was "put back the Great in Great Britain". People are sick of being praised for "punching above your weight"; Britain, they feel, should keep clear of foreign adventures in Brussels as in Baghdad. It seems that a great swathe of post-industrial England no longer much cares who governs ("they’re all the same") as long as they keep the front door shut. And this isolationism also means that respect for the American connection is evaporating, just as Brexit means that the British connection loses its importance for America.

That’s deeply bad news for London’s political elite. For two generations, its self-assurance has hung on Trident and the tattered "global power" illusion, both reluctantly supported by the United States. No longer respected by its subjects, can that ruling caste survive in Little-England isolation, cut off both from Europe and from the "special relationship"?

The sound of my third demonstration was laughter, prancing children playing recorders, friends clapping well-met friends on the back – "You here? I never thought …" This was the March for Europe, just over a week ago. It was the new mode in protest. No colliery pipe bands, no trade union banners or Socialist Worker placards, but a torrent of 40,000 people alerted by social media who carried their own home-made posters.

They were mostly young. They didn’t fight, as their grandfathers had in the Suez riot of 1956. They didn’t cry tears of shame and helpless anger, as some of their mothers had as they walked along in 2003. They were cheerfully sure that something as ridiculous as ripping them out of Europe couldn’t last, and they may be wrong about that. Everyone said: "Well, Scotland will go independent now. Inevitable, isn't it?" When I said that the track to independence was not that straight, they seemed disappointed.

This was the optimistic, multicultural part of England. They feel let down by knaves and idiots, but not abandoned. They have no more confidence in those who govern than voters in Sunderland or Dudley. But they have self-confidence; they trust that in time they will lead their country back into the real world.

In other parts of England this summer, "independence day" has not brought the sun out. "A stunning blow has been delivered to the Establishment"– but with the help of an agile faction of that Establishment which has scrambled back into government. What happens when the emptiness of its promises becomes clear? Meanwhile, after a dirty campaign, real political power in England lies in the gutter. We don’t yet know who will pick it up. But as they bend down, they may hear tapping from underneath.