Sport minister Tracey Crouch has resigned over delays to cut fixed-odds betting from £100 to £2 a time.
The crackdown on fixed-odds betting machines will now happen next October, rather than April, as announced by Chancellor Philip Hammond on Monday.
In her resignation letter, she wrote: "From the time of the announcement to reduce stakes and its implementation over £1.6bn will be lost on these machines, a significant amount of which will be in our most deprived areas including my own constituency."
She added: "I know there is never a good time to resign and appreciate that this will be an unwelcome distraction but as the Secretary of Digital, Culture, Media and Sport said in the House this morning, it is a fact of Government that ministers must adhere to collective responsibilty and cannot disagree with policy, let alone when it is policy made against your wishes relating to your own portfolio."
'With great sadness I have resigned'
The MP for Chatham and Aylesbury failed to appear in the Commons earlier on Thursday to answer an urgent question around the policy's timing.
Culture Secretary Jeremy Wright answered the questions and said she was "doing an outstanding job as minister for sports and civil society".
"She deserves a large part of the credit for the substantive change that this Government is making," he said.
Labour MPs repeatedly shouted from the benches: "Has she resigned?"
Mr Wright added on Thursday that there was "no delay" to the plans to slash the max spin down, but they won't come into effect until October.
Read the letter of resignation in full below:
It is with great sadness that I write to tender my resignation as Parliamentary Under Secretary for Sport and Civil Society.
Your personal support earlier this year for a reduction in the stake of fixed odds betting terminals was incredibly welcome and a real reflection of your ambitions set out in your very first speech on the steps of Downing Street to support vulnerable people against the power of big business.
I cannot begin to explain how many people got in touch to congratulate Government on its stance, including addicts, their families and also, sadly, those who have been left behind after loved ones took their own lives as a consequence of addiction.
Unfortunately, implementation of these changes are now being delayed until October 2019 due to commitments made by others to those with registered interests. From the time of the announcement to reduce stakes and its implementation over £1.6bn will be lost on these machines, a significant amount of which will be in our most deprived areas including my own constituency.
In addition, two people will tragically take their lives every day due to gambling related problems and for that reason as much as any other I believe this delay is unjustifiable. The alignment of the stake reduction with an increase in remote gaming duty was a condition put on by the Treasury to provide fiscal neutrality but is not a technical necessity, so this is no reason why implementation cannot come in sooner than October.
I know there is never a good time to resign and appreciate that this will be an unwelcome distraction, but as the Secretary of State for Digital, Culture, Media and Sport said in the House this morning, it is a fact of Government that ministers must adhere to collective responsibility and cannot disagree with policy, let alone when it is policy made against your wishes relating to your own portfolio.
I would like to place on the record my enormous gratitude to the amazing team of civil servants who have helped me over the past three and a half years in post. I am very proud of what we have achieved in that time, including the sports strategy, the gambling review, the Civil Society strategy and of course the most recent loneliness strategy, which I was humbled to lead on your behalf.
I have had the privilege of meeting many charities, volunteers and social enterprises working collectively to support and enhance civil society; cheered on our summer and winter Olympic and Paralympic athletes; and have attended almost every major sporting event meeting great sports men and women, past, present and future.
I hope you understand my position and accept my resignation with the sadness it is tended.