PARLIAMENT stands on the brink of what could be its most massive shock in its entire history.

The Palace of Westminster is crumbling and is in dire and urgent need of multi-billion pound surgery. Unlike London Bridge, this great edifice is not in danger of falling down - not just yet anyway.

But even politicians have at long last come round to the view that this cannot go on for much longer.

The alarming state of disrepair has got to be confronted - and quickly - before it becomes unsafe.

They recognise that this will cost billions of pounds - £4 billion is one figure hinted at - but early estimates, as always in these cases, will increase as the workmen discover scores of so far unknown weaknesses when they probe this edifice, thus adding immeasurably to the cost.

Some have suggested the pulling down of the building - sacrilege! - and replacing it with a modern one. This would probably be the cheapest option, but even the most pennywise and unromantic of MPs recognise this would be a catastrophic error.

It would deprive London of its most famous landmark and could have a dire effect on the current flourishing tourist trade.

The big problem is what to do with the 600 MPs, their staff, the press and the scores of other “camp followers” who would have to move out for some six years while this work goes on.

Adapting the nearby Department of Health building - or part of it - into a debating chamber is one option being considered.

Another is the bizarre idea that a floating Parliament should be moored in the Thames close to the existing building.

That idea may not be so dotty as it sounds, and the Labour leader Jeremy Corbyn has said it deserves to be looked at.

Whatever decision is reached, we are looking at what will be perhaps the biggest removal job mankind has ever seen.

l NO wonder David Cameron regularly flunked reaching a decision on a new runway for Heathrow Airport. It is political dynamite.

He has lumbered his successor Theresa May with making a decision that is expected to be announced quite soon.

Top industrialists and others - notably former Chancellor George Osborne - insist that a new runway here is vital for the health of Britain’s economic future.

But on the other side of the coin, a decision to go ahead would alienate thousands of people - many Tory supporters among them - who live under and around the Heathrow flight path.

Meanwhile Zac Goldsmith, Conservative MP for Richmond Park, has issued a stark warning that if this development goes ahead, it could cost the Tories many MPs at the next general election.

And he has vowed to resign his seat and fight a by-election - presumably under a non-Tory banner - if the runway is approved.

This will be a huge test for the Prime Minister.

Will she put the interests of her own party before those of the nation’s economic wellbeing?

And where does the Foreign Secretary, Boris Johnson, whose constituency is in the affected area, now stand on all this?