The former chair of the board of Stonewall, Labour MEP Michael Cashman, says Ben Summerskill is “in danger of undermining” his legacy with the gay rights charity due to critical remarks on Twitter.

Mr Summerskill, who resigned as chief executive of Stonewall last month, published a series of tweets expressing his disappointment at not being able to attend last night’s Stonewall Equality Dinner at the Dorchester Hotel in central London.

He told Conservative MP Margot James that Stonewall’s Acting Chief Executive Ruth Hunt had insisted that he was not present at the event marking the charity’s 25th anniversary.

Mr Summerskill joked about his predicament in tweets to a range of celebrities and Stonewall supporters who were at the Equality Dinner.

He also tweeted the sponsors of the Equality Dinner, Aviva.

And Stonewall employees, who just weeks ago he was in charge of.

Mr Summerskill also suggested that Jacqueline Davies, who is stepping down as chair of the board of Stonewall in May, had been pushed from her post – claims which Stonewall has denied to PinkNews.

Ms Davies said she was retiring after nine years in post, along with Stonewall’s Deputy Chair of the Board, Nigel Bentley, but Mr Summerskill suggested otherwise.

He also claimed her time on the board had been “eventful”.

Mr Summerskill also posted a bizarre reference to the Chair of Stonewall’s handbag.

The former Stonewall boss then posted this update when Ms Davies bid for an item at an auction.

Last month, shortly after he announced his resignation, Mr Summerskill posted this Tweet to Ms Davies

The former chair of the board of Stonewall and one of the charity’s co-founders, Labour MEP Michael Cashman, said he was dismayed by Mr Summerskill’s behaviour on Twitter. It comes just days after Mr Summerskill caused uproar having accused the Liberal Democrats of being “cynical” and “opportunistic” in their support for equal marriage in 2010.

Mr Cashman told PinkNews.co.uk that Mr Summerskill’s comments about Stonewall’s board arrangements was a matter of deep regret.

“My reaction to that, as someone who was chair of the board is that whatever happens within a board should remain within a board because by repeating something outside you can damage that organisation and damage the causes of that organisation [so you] should keep stum.”

The MEP defended Jacqueline Davies and Mr Bentley from criticsm. He said: “The politics of boards and the politics of people when they leave organisations can be quite unpleasant. She was a remarkable chair, she had a remarkable deputy, and she should be judged on her time as chair of the board. My advice to Ben Summerskill would be that you are no longer the chief executive of Stonewall, you are no longer representing Stonewall… get on with the rest of your life, have the courage to let things go.

“It’s difficult. I did that. The brilliance about letting things go is that they grow beyond your wildest dreams and thereby they pay tribute to you.”

Mr Cashman said Mr Summerskill should feel no ill feeling regarding his absence from last night’s Stonewall Equality Dinner. “That is current practice, when you stand down you are separated from the organisation because the acting chief executive or the new chief executive needs to occupy the space – otherwise there is confusion about who is speaking for the organisation,” the MEP said.

“And there were many years when me and other co-founders were not invited under Ben Summerskill’s tenureship to the Stonewall Diners – and it doesn’t matter you know, I’m a bit like Groucho Marx, I don’t want to go to any party that I’m invited to, I’d rather go to the ones that I’m not.”

Mr Cashman advised Mr Summerskill to take a “deep breath, stand back and let the organisation get on what it has set out to do, and if he doesn’t, Ben’s in danger of undermining the work that he’s put into Stonewall, which is part of where the organisation is now.”

He added: “You can’t take back what’s been said but what I think you should therefore enter into is a period of silence and reflection.”

Update: Mr Summerskill now claims that this news story was “made up”, despite it consisting primarily of his own Tweets.