A national newspaper that printed his maiden speech in full and tipped him for the top has now branded him a “wrong ‘un”, told him that he’d made a fool of himself and behaved disgracefully.
Well, he had just labelled Mrs May’s government a “s*** show” and later said “I cannot continue to support an administration that cannot function”.
Some fruity vocabulary, perhaps, but nothing that every MP doesn’t hear on a daily basis on the green benches and not terribly remarkable, perhaps.
No, that’s completely wrong.
It is remarkable because a competent, ambitious Remainer, who is normally loyal to his Remainer Prime Minister, has chosen to join a rebellion just as his party starts the helter-skelter of horror that will run straight into Budget Day next Monday.
Before that happens, however, this backbencher got a slap: a nasty, personally insulting salvo carefully placed in the popular press by 10 Downing Street.
But how on earth has Theresa May managed to alienate backbenchers like Mercer?
Her ship emerged from the party conference if not buoyant, certainly with any holes below her water line plugged and steaming full ahead.
It helped that any contenders for her captaincy had recently wrecked themselves and that, cynically, they didn’t want this perilous job when the current incumbent was on an almost even keel.
The skipper, to use one of May’s catchphrases, was ‘just about managing’ and, as long as she was steering through the squall while taking on more water, why replace her? Let her flood and sink when the storm was past.
So, with as fair a wind as could be expected, May sailed for Europe with a harbour in sight and the icebergs of the Northern Ireland border issue, customs unions, backstops and any amount of EU blather probably avoidable.
With her party relatively quiescent and the Opposition all at sea, her resilience and courtesy had won her a great deal of goodwill, especially as things seemed to be nearing a close.
But it all went wrong. Westminster and Fleet Street held their breath: would the Prime Minister stamp her stylishly shod foot? Would the talks founder? Could a rabbit be conjured from a top hat? No, as the nation was shrieking for an end, she asked for yet more time!
And that time, of course, has a cost as extended membership of the EU would have to be paid for but with no benefits. In a trice, May achieved the impossible and united all factions: sadly, they united against the way she was handling things.
It’s this indecisiveness which has caused Johnny Mercer and others to nail their colours to the mast. Or, whisper it softly, did they sense an opportunity?
On Tuesday, May weathered a stormy meeting of her Cabinet and on Wednesday she survived the much trumpeted meeting with the 1922 Committee of backbench MPs to which, it is claimed, she had been told to “bring her own noose”.
But hanging over her there is always the threat of “letters of no confidence”, 48 of which would spark a leadership showdown. However, it takes courage to submit such a letter as the whips always find out, and its a betrayal from which there is no retreat. My guess is that the total currently falls a long way short.
Yet next week’s Budget, and subsequent vote, could prove really tricky. The Brexiteers suggest that May and Philip Hammond have pledged billions to ‘plot the path out of austerity’, yet wads of extra revenue will now have to be found to pay Brussels for the extended transition period, jeopardising that promise. So, Brexiteers argue that they would be justified in voting against the Budget and if the Government can’t carry the Chancellor’s plans, it must fall.
So, where would that leave Captain Mercer and a handful of other, articulate competents who aren’t recognised ‘big beasts’ but who aren’t yet scarred?
Politics is all about communication and this is where May has failed and Mercer has succeeded: his ability to get through to people has spawned this very column.
But if we ignore the bigger contest of a general election just for a moment, where do such people go as the Tory party hits the rocks?
Well, having told the world that you could no longer support May’s Government usefully absolves you from the ensuing mess.
Then there’s Mercer’s attractive statement “everyone must choose a hill to perish on...” suggesting that he would place issues about which he felt passionately above his party and career.
Good stuff: will he and his confederates form a new party with different values? Might they change the way that our failing democracy works? Or will they simply choose that same slope to launch their own ship whose bows point at Number 10? Time will tell.
Patrick Mercer OBE is a former Conservative MP. He was previously a soldier.