His replacement has yet to be announced.

Mr Opperman confirmed in a letter issued via social media this morning that the Prime Minister had informed him relived him of his duties as pensions minister on 8  September.

He had served as pensions minister since June 2017 and his five-year tenure made him one of the longest serving pensions ministers.

He had previously stepped down as part of a ministerial exodus calling for former Prime Minister Boris Johnson to step down but had returned to his role shortly after Mr Johnson announced his resignation.

Mr Opperman said: “The leadership contest is over, and the new team, and new PM, is entitled to choose their personnel to take matters forward. My successor, and the new government team, will have my full support.”

He had delayed announcing the end to his tenure as Minister for Pensions and Financial Inclusion out of respect for the period of mourning for Queen Elizabeth.

He added: “We passed the ground breaking Pensions Schemes Act through Parliament. The Act has secured our pensions on an ongoing basis and has unquestionably made them safer, better and greener. Safer by stopping scams and preventing crime. Better by bringing forward the pension dashboard – a digital revolution for pensions – creating one place to see all your pension pots, personal and state. This will go live in 2023. It will change pensions forwever. And greener by harnessing pension power to play a huge part in delivering Net Zero to the UK by 2050, with TCFD and more.”

He added that much still needs to be done for financial inclusion, and that he will continue to champion 1% default workplace savings to fix this from the backbenches.

He concluded that there remains much for his successor to do including expanding automatic enrolment, to professional trustees, proper measurement of value for money, expanding Superfunds, illiquid investmet and CDCs, and ensuring a better system for individual defined contribution retirement planning.

Mr Opperman remains as MP for Hexham.

He said he will now concentrate on his constituency, backbenches, and young baby.