SCHOOLS will crumble, a futile war kills and maims and hundreds of thousands will be thrown on the dole – yet the Con-Lib Dem coalition sails merrily on.

But throw in a row about an issue few people care about and neither of the parties truly wants – the referendum on the alternative vote (AV) system – and suddenly the Government is in mortal danger.

How can the biggest obstacle in the path of the Cameron-Clegg chariot be something the public regards with a yawn, rather than the jobs, schools and tragic war that matter so much more? After all, remember that even Nick Clegg once described AV as a “miserable little compromise” – before he miraculously became its biggest supporter.

The answer is that the referendum row – nearly 50 Tory backbenchers oppose its staging next May – flows from a belief that David Cameron deceived his own party at the moment the coalition was born.

Worse than that, the Prime Minister is accused of continuing that deception by publicly stating he opposes AV, while secretly hoping the public votes “yes”.

To recap, Mr Cameron convinced his party, during those post-election days of drama, that the referendum simply had to be offered to prevent a Lib-Lab deal that would keep Gordon Brown in No 10.

Unfortunately, Mr Clegg now admits Mr Cameron’s claim that Labour had offered AV immediately – without a nationwide vote – was untrue, begging the question who misled whom? Conservative right-wingers suspect it was their own leader, having long accused him of betraying Margaret Thatcher’s legacy. It is a wound that can only fester.

Meanwhile, conspiracy theories are undermining Mr Cameron’s insistence that he wants to stick with first-past-the-post, rather than switch to AV, which is more likely to deliver future coalitions. Many Tories believe the Prime Minister fears the Lib Dems will walk away if the referendum is lost, making a “yes” vote a price well worth paying to keep him in Downing Street for five years.

Even if coalition does survive, how can its twin leaders convincingly oppose each other in live TV debates in 2015, having been paton- the-back partners for so long?

Can it only work if each can urge their supporters to give second preferences to the other party – as conveniently allowed by AV?

Some believe Mr Cameron now secretly backs that solution.

It explains Tory fury over the referendum – even if it doesn’t explain Lib Dem silence on those important issues where the Tories ride roughshod.

ADMITTEDLY, another small dark cloud emerged on the horizon yesterday – the Prime Minister’s plan to end the luxury of “council housing for life” for new tenants.

It was quickly pointed out that Mr Cameron himself, just before the election, had dismissed Labour “scaremongering” on the issue, saying: “We have no policy to change the current or future security of tenure of tenants in social housing.”

Within hours, Lib Dem deputy leader Simon Hughes had dragged himself away from his August slumber, rejecting the idea with the memorable statement: “It is a prime ministerial idea. It has no more validity than that.”

Hmmm. I’m not sure this notion – “this Cameron fella from central London, he doesn’t speak for the government”, to paraphrase – is going to work for the poor old Lib Dems.