The civil liberties and human rights specialist is best-known for the ‘Brexit cases’ – which culminated in the Supreme Court decision in September 2019 that the prorogation of Parliament by Boris Johnson was unlawful.

Previously, in December 2018, the European Court of Justice said the UK could invoke Article 50 unilaterally and withdraw from the EU without the agreement of all member states.

In a video interview, Mrs Motion said of the Article 50 case: “I’ve still got a tingle. I sat there [in the Luxembourg court] and thought, ‘Gosh, our team has done that. Our team has brought this to Europe.’ It was quite extraordinary; you don’t [always] think about the bigger picture when you’re busy trying to get the case done.”

On the Supreme Court case, she commented: “The spider brooch [worn by Lady Hale to deliver the judgment] was so funny, because I did feel like a spider in the middle – trying to organise and coordinate, to work with people and cajole and encourage and bring everybody together. It was just an extraordinary feeling, but one of immense satisfaction.”

With the Brexit cases (and others), Mrs. Motion said you have to keep faith: “[You] often lose in the first round, and often in the second round, but then in the Supreme Court, you win. So, it’s not losing faith in the arguments that you’ve got, and [having] the strength of commitment to see it through.

“There are cases that you lose, and you I don’t like losing, [but] know you have done the very best you possibly could, and say hand on heart, the ones that we’ve lost, we’ve worked as hard and done as much as we possibly could.”

Mrs Motion worked in Scotland for firms including Thompsons and McGrigors, and then in New Zealand, before joining Balfour and Manson in 1993, and becoming a partner in 1997. Joining the firm was “like coming home – having been in different firms in the UK, and New Zealand, it felt like I was putting my hand into a glove.”

The biggest change in her career has been “technology – by a million miles, in terms of the need to respond quickly, [and] the speed at which matters move and require to be done.”

Reflecting on the cases that gave her most satisfaction, she added: “Sometimes it’s the very quiet, individual cases. I think about a young child I did a cerebral palsy case for years ago. We got a settlement for that child at the age of six, and that child, now an adult, is getting money on an annual basis and will live for a long, long time. It’s a massive settlement but knowing that person is financially secure for the rest of their life, and for their parents to know that, is just massive. I’m so fortunate that I’ve had so many opportunities to do amazing work.”

Mrs Motion spent many years as executive chairman at Balfour and Manson and said the secret to balancing managerial responsibilities with client work was “a lot of hours, a lot of hard work, but I also took some coaching to learn how to make sure I put management at the top of the list, as well as work commitments. I [also] had a fantastic team; you can’t do it without a team.

“I think back to the partner I worked for in New Zealand, who always said, ‘Make a decision. Make any decision.’ It might be wrong, it might be right, but it’s a failure to make a decision that’s the problem and make it quickly. That’s been one of my mantras over my career - just decide and get on with it.”

Her biggest regret? “What frustrates me most is access to justice. We turn away cases that we can’t take on because legal aid is just not viable, and people can’t pay for it.”

Asked what legacy she might leave behind, Mrs Motion added: “If anything, I’d like [people] to remember that I tried to help other women come behind me and do exactly the same thing. A few lawyers out with the firm have said that to me, so that’s incredibly touching.

“Other than that, I worked hard, had fun, and I hope a few people will remember me for a few years. But as Churchill said, there are a lot of indispensable lawyers in graveyards. So, knowing I’ve done my bit, and if I can get out of here without having caused chaos and created any disasters, then I’ll take that as my legacy.”