Emily Thornberry has accused Labour’s ruling body of trying to “overturn” the result of last year’s leadership contest, and claims she was branded a “traitor” by Tom Watson after voting against the Labour Government.

The Shadow Foreign Secretary says she has been “disgusted” by attempts to stop Jeremy Corbyn being automatically placed on the ballot for the current contest, as well as the tightening of leadership election rules – which have been seen by many as an attempt to curb support for Corbyn. She says the “party hierarchy”, acting through the National Executive Committee (NEC) has been attempting to “put the party’s members back in their box” by deposing the current Labour leader.

In a letter to local party members in her Islington South constituency, which neighbour’s Jeremy Corbyn’s own seat, Thornberry writes:

“Here we are now, less than a year after Jeremy’s overwhelming victory, and the party hierarchy – through decisions of the National Executive Committee – is attempting to overturn that result, quash Jeremy’s mandate, and put the party’s members back in their box. And they are doing so in the most naked way.

“I was disgusted to see the attempts to try to stop Jeremy from getting on the ballot. And then, if that wasn’t bad enough, hundreds of thousands of fully paid-up Labour party members were excluded from taking part in the election, having been told the opposite when they joined. Third, your membership fees were spent on securing that decision through the courts. And then lastly, registered supporters, who had been told they could be involved in the Leadership election, were then told that they must increase their donation to £25 within two days to remain eligible for a vote.”

She also hits out at New Labour, who she says began to use party members’ unhappiness as a litmus test for whether they were doing the right thing.

And she claims Tom Watson, now deputy leader and a critic of Corbyn, once called her a “traitor” for voting against the government on the contentious 90-day detention policy, which eventually failed after a large Labour rebellion.

That charge is particularly relevant to current debates in the party, as some have speculated that BFAWU General Secretary Ronnie Draper has been suspended from the Labour Party for his use of the word “traitor” on social media.

“What had begun as the necessary modernisation of the Labour Party in 1994, showing how a belief in a dynamic market economy could be combined with the drive for social justice and the transformation of public services, had become distorted into an agenda where the test of every new policy from the leadership was how much it would antagonise the Labour Party’s core membership,” Thornberry writes.

“Tuition fees, the attempt to marketise the NHS, the careless disregard of long cherished civil liberties and the drive to war in Iraq were being imposed by a leadership who convinced themselves that, if the members hated it, they were doing something right.

“When I walked through the voting lobbies against the attempt to impose 90 days’ detention without charge in 2005, Tom Watson –then one of Tony Blair’s whips – growled at me that I was a ‘traitor’.”