I can go back a long way on this.

In 1970, with a squad still stuffed with World Cup-winners, we were convinced it would be an England versus Brazil final; still more so after the gripping 1-0 group stage defeat, which included Gordon Banks’s astonishing save.

Not for the last time, a late German comeback put paid to that.

West Germany were once again the stumbling-block in 1972, come the European Championships.

Green-shirted Günter Netzer laid waste to the English midfield, looking (in my mind’s eye) like a cross between Herzog/Kinski’s Don Lope de Aguirre and a particularly long-striding member of Status Quo.

In truth, the 1970s were a dismal decade for English international football; but still we found reasons to believe.

In 1974, we were knocked out by Poland - POLAND!

Yet Jan Tomaszewski and Co turned out to be good enough to finish third in West Germany’s World Cup.

Two years later, our nemesis was Czechoslovakia - and they ended up as European champions.

In 1978, elimination by Italy, though disappointing, seemed less than a disgrace.

And so it went on: in 1982, we exited the World Cup undefeated, able to blame the dodgy structure of a competition with two group phases.

1984: while we could hardly believe our eyes when Jesper Olsen’s Denmark ran us ragged, they were good enough, rather like Poland 10 years earlier, to reach the semi-finals of the competition proper; so we could not be too far off the required standard, could we?

1986: the Hand of God; say no more.

In more recent years, it has been largely a case of torment by penalty shoot-out - a confection all but guaranteed to reinforce the losing side’s belief that they are just a fingertip away from greatness.

With each new thwarted campaign - including on home soil in 1996 in the Euros, when England had a genuinely impressive team - the flags of St George sprouted more copiously, the belief that success was just around the corner grew more defiant.

Not even the slings and arrows of Ronaldinho’s free-kick in 2002 or Frank Lampard’s disallowed "goal", which bounced well behind the German goal-line in 2010, could shake our faith that next time it would be our turn.

Then, four years ago in Brazil, something snapped.

It was not I think the defeats by Italy and Uruguay that heralded the beginning of the end of our delusions of grandeur.

It was the failure to beat even a Costa Rica team who had already qualified for the knockout stages.

Yes, true to form for an England opponent, they turned out to be much stronger than they had been given credit for, almost reaching the World Cup semi-finals.

Nonetheless, a light-bulb had come on and a question started to nag away: could a team unable to break down a Costa Rica side for whom victory was not strictly necessary really be anywhere close to good enough?

Which brings us to Euro 2016, where the colossal scale of our 50 years of folly was finally rammed home by defeat at the hands of Iceland, a nation with around the same population as Croydon.

The scales fell from our eyes, the penny dropped and in a collective act of contrition and enlightenment, we discarded the lunatic faith that had sustained us for half a century.

The false-start of Sam Allardyce’s 67-day managership seemed, initially, to confirm the good sense of this new realism.

Life, though, is full of paradoxes.

A mere two years on, and with a new England team in the World Cup semi-finals, it suddenly seems clear that the collective loss of belief we experienced post-Brazil 2014 and Iceland was exactly what England needed to pick themselves up by the bootstraps and turn themselves into genuine contenders.

By turning down the pressure-cooker in which generations of England players have been obliged to operate, the space has been created for a level-headed young manager, Gareth Southgate, to try things, to do the job his way, to some extent freed from the weight of public expectation.

Of course, with the ship now back afloat and the interjections of "It’s coming home" growing less ironic by the minute, the pressure is quickly ratcheting back up to more normal levels.

Does this signal a reversion to type, with flickerings of promise set to be snuffed out before they truly catch light?

We will start to find out the answer over the balance of this week.

In the meantime, thank you, Iceland, for administering the jolt that brought us to our senses and created the conditions in which a new culture could begin to flourish.