Felicity Cornelius-Mercer said the Cabinet system “stinks” and “treats people appallingly” after her husband was removed as veterans affairs minister on Tuesday.
Plymouth Moor View MP Mr Mercer appeared to be angry about Ms Truss’s move, saying he was “disappointed” but that the new PM is “entitled to reward her supporters”.
In a public letter, he also suggested he could quit the Commons, stating: “I have to accept that I will never possess the qualities required for enduring success in politics as it stands, and to be fair to my wonderful family, I must consider my future.”
His wife tweeted a picture of a character from The Muppets dressed up as Ms Truss and gave an account of her husband's meeting with the new PM.
Ms Cornelius-Mercer said: “He asked her ‘why would you do this, who is going to be better at this role than me, which of your mates gets the job, you promised a meritocracy?’
“PM – I can’t answer that Johnny. This system stinks & treats people appallingly.
“Best person I know sacked by an imbecile.”
On Wednesday morning she said that she had "no regrets" about the comments.
Ms Truss handed the veteran’s affairs brief to Armed Forces Minister James Heappey at the Ministry of Defence.
Retired Major General Rupert Jones said it was “deeply depressing” that Mr Mercer was sacked.
He added: “[Mr Mercer] cared and fought for veterans with tireless passion.
“Few people are irreplaceable in politics, but when it comes to veterans, he is close to it - veterans will be the losers in this decision.”
Former Chief Prosecutor Nazir Afzal said: "The treatment of veterans, some homeless and others broken in many ways is a scandal and Mr Mercer has been a strong advocate for them.
"Ms Truss’ decision to sack him is a terrible mistake and one she will regret."
Lord Dannatt, former head of the British Army, said it was "understandable" that Mr Mercer was disappointed but "most unfortunate" that his wife had insulted the Prime Minister.
He asked her ‘why would you do this, who is going to be better at this role than me, which of your mates gets the job, you promised a meritocracy?’
PM - I can’t answer that Johnny
This system stinks & treats people appallingly
Best person I know sacked by an imbecile @trussliz pic.twitter.com/RZGblGA1tx
— Felicity Cornelius-Mercer (@mercer_felicity) September 6, 2022
He told the Standard: "Johnny has worked extremely hard in the best interests of military veterans and should be commended for the enormous amount he achieved. He was delighted to be appointed by Boris Johnson and is understandably disappointed.
"But I think what Johnny has to realise is that the office and appointment of veteran's minister is bigger than just one person and the fact that James Heappey has taken over means his role is not necessarily over and his fine work can continue.
"It was most unfortunate that Johnny's wife called the Prime Minister an imbecile. That should not have been said. It is better that politics be left to politicians."
A personal statement.
Time for others to step up. I will be spending time with my family and doing no media requests. pic.twitter.com/8mFgIza9WL
— Johnny Mercer (@JohnnyMercerUK) September 6, 2022
New Deputy Prime Minister and Health Secretary Thérèse Coffey defended the PM’s decision.
“I’ve very conscious that Liz has appointed a really diverse cabinet,” she told the BBC.
“I'm delighted that James Heappey will be taking on that role and will be attending cabinet this morning.
“I know that the Prime Minister is very focused on delivery and focused on the pace and that is what we will be aiming to achieve including for our armed forces and indeed our veterans.”