Nick MacKinnon, who taught the PM at posh private £49,000-a-year Winchester College, slammed his "selfserving, opportunistic" former pupil for "the way he turned out".
And he vowed to vote for Keir Starmer's party to punish Mr Sunak for his "completely unforgivable" backing of Brexit, which he says has put the country back 20 years.
The maths tutor and ex-housemaster told this newspaper: "I don't know how he sleeps at night." The criticism comes despite the Prime Minister, 44, and his wife Akshata Murty donating more than £100,000 to the school he attended from the age of 13 to 18 and left in 1998.
Mr MacKinnon said: "I remember him only as a boy at the back of class.
"I recall little about him as a pupil but his achievements at Winchester are not in dispute. He was a very good boy and I am sorry for the way he has turned out, which was to become wildly opportunistic." He added: "I will be voting for Labour against Sunak. In my mind he has to be punished by my one tiny little vote, but that's what I will do.
"It is a punishment vote for Brexit. If I'd done what he did over Brexit, I'd be struggling to get to sleep every night.
Denne historien er fra June 02, 2024-utgaven av The Sunday Mirror.
Start din 7-dagers gratis prøveperiode på Magzter GOLD for å få tilgang til tusenvis av utvalgte premiumhistorier og 9000+ magasiner og aviser.
Allerede abonnent ? Logg på
Denne historien er fra June 02, 2024-utgaven av The Sunday Mirror.
Start din 7-dagers gratis prøveperiode på Magzter GOLD for å få tilgang til tusenvis av utvalgte premiumhistorier og 9000+ magasiner og aviser.
Allerede abonnent? Logg på
Kulusevski: These are my games...we can hurt Reds
EJAN KULUSEVSKI is relishing he first of three huge meetings ith Liverpool - insisting ottenham have the tools to hurt\" Arne Slot's Premier eague pace-setters.
Steely Keely
SPOTY queen has 'already beaten 800m world record'
On the Rocky road to stardom
ROCKY FLINTOFF is already the youngest cricketer to be picked for an England Lions tour.
Drivers go green
Gold, yellow and purple cars are also top choices..but pink stinks
GOING THE EXTRA MILL
Mirror sees our biggest paper recyclers working flat out
It's bank of mum & debt
MUMS and dads who helped their kids on to the property ladder now want their money back as they battle the soaring cost of living.
I'm working in a winter wonderland
Coolest grandad spends Xmas in Antarctic with penguins and seals
If it was my child missing I'd want people rushing to help
INVESTMENT banker James Walker leads a double life.
People will hate Cindy even more after this story
Actress on festive EastEnders bombshell
FORCES STAY ON FESTIVE STANDBY
10,000 ready for any Xmas action