Ruth Davidson said being “hopelessly conflicted over Brexit” was one of the reasons she resigned her leadership of the Scottish Conservative party.

She also criticised the way Boris Johnson has suspended parliament, saying it looks like a politically motivated decision.

Appearing on ITV’s Lorraine programme for her first TV interview since stepping down in August, Davidson said she was not told the reasoning behind the decision to close parliament.

Judges at the supreme court are hearing evidence about the move to close parliament for five weeks ahead of the Queen’s speech and in the lead-up to the 31 October Brexit deadline.

Play Video 1:55 Ruth Davidson announces her resignation as Scottish Tory leader – video

A legal challenge argues the decision was made to limit MPs “frustrating or damaging” the prime minister’s plans to leave the EU.

Asked about the move, Davidson said: “I think it was done in a bad way, but the idea that a prime minister doesn’t suspend parliament in order to bring forward a Queen’s speech and a legislative agenda, up until recently that happened almost every year.

“I was quite close to David Cameron and Theresa May. I’m not close to Boris Johnson. I’m not going to pretend that I’ve ever been part of his inner circle – I haven’t – so I don’t know why the government chose to do that and that’s one of the things the judges are going to be deciding, and what the Scottish case looked at.

“They certainly didn’t manage to take the country or the parliament along with them as they did it, and there are questions about that,” she said.

Following Cameron’s comments that Johnson does not believe in Brexit but instead puts his own interests first, the Edinburgh Central MSP said: “I don’t know what’s in his heart.

“I don’t know whether he desperately believes in Brexit or he doesn’t believe in Brexit and I’m not going to pretend that I do. But I think people can tell if politicians are basically telling the truth or not and if they can tell if they mean what they say.”

Davidson said Brexit and her family were behind her decision to step down.

“I’ve always put my work first and the job first and the role first, and sometimes that means my wider family has suffered, and now I’m making a different choice because I’ve been hopelessly conflicted over Brexit,” she said.

She added: “That conflict made it harder to be as good a leader, as clear-sighted a leader, as I had previously been.

“I’m professionally proud – I want to do a good job and I wasn’t performing at the level I had done before. This weekend was the first time in the best part of a decade where I didn’t work any part of Saturday or Sunday,” she revealed, and when asked whether it was a strange feeling replied: “It felt naughty.”

Questioned about her apparent lack of ambition to become prime minister, she said: “I’ve got enough self-knowledge to know that one of the reasons people say (she would make a good leader) is because they knew that I’m never going to put myself forward for it.

“It’s the David Miliband thing – a king across the water is only attractive if they stay across the water, as soon as they actually get in the mix they become much less attractive of an option, I’m not kidding myself here.”