Labour's shadow education secretary Lucy Powell has resigned this afternoon after less than a year in the job.
The MP's resignation letter makes it clear that her decision is a protest against Labour's leader Jeremy Corbyn who, Ms Powell writes, she does not have confidence in to lead an effective opposition.
"It is increasingly clear that your position is untenable," she says.
Ms Powell is the latest in growing list of of shadow cabinet members to quit today in an effort to bring about a change in Labour leadership in the wake of the Brexit vote.
Having been appointed in September, she has had limited time to make a real mark in the role. But facing a government struggling to deal with teacher shortages, exam reform and squeezed school budgets, Ms Powell also had plenty of scope for challenging ministers.
In today's letter, she claims the government's embarrassing U-turn over full forced academisation as a Labour victory, though many would attribute the climbdown as having more to do with Conservative opposition to the policy.
Ms Powell writes: "We have forced the Government to drop their detrimental plans to force all good and outstanding schools to become academies.
"I have challenged the government on their failure to recruit enough teachers, their failure on school place planning and highlighted the huge budget pressures schools are now facing."