It’s said to be the Queen’s favourite ice-breaker, though on this occasion the question came from someone else at Buckingham Palace.

“Just from North London,” Vivien Rose replied in 2013, as she waited to be invested as a Dame Commander of the British Empire. But in her head she was shouting “Yes, actually I have!” because her route to the High Court then — and to the UK Supreme Court now — has been unique.

The anecdote is recounted by Anthony Inglese, a former senior government lawyer who now writes excellent profiles for Counsel magazine. Perhaps Rose told him the story because she, too, had been a government lawyer before becoming a judge.

Educated at a London comprehensive, the first person in her family to become a lawyer — these attributes are common enough in new judges these days. Even being the first woman to be offered a tenancy at her chambers — Monckton Chambers, in her case — is not so unusual for someone of her generation.

And that’s how she found herself practising competition law, which she had enjoyed studying for the BCL degree at Oxford after taking her first degree at Cambridge. “I wasn’t intending to practise in it but my desire for a tenancy was at the time all-consuming,” she told Inglese. “I remember standing in Gray’s Inn Square one summer’s evening and saying to myself, ‘I so desperately want to do this’.”

But then she took an unusual path for someone of ambition, giving up private practice and any chance of becoming a QC to join what is now the government legal service. Rose helped pilot the giant Financial Services and Markets Act 2000 through parliament and implement it afterwards. “It was the largest bill to go through parliament at the time and we had to draft over 100 statutory instruments, some of which were mini-statutes in themselves.” No other judge has had such a close familiarity with a tool of the trade.

Equally unusual was her work in international humanitarian law at the Ministry of Defence and her secondment to the Office of Speaker’s Counsel in the House of Commons. But the key move for Rose was to become a part-time tribunal chair at the Competition Appeal Tribunal in 2006.

That’s what reporters would instinctively describe as her first step on the judicial ladder. But it would not have looked like that at the time. Very few judges make the leap from tribunals to what is facetiously described as the judiciary’s uniform branch. None has made it before from a tribunal to the highest court in the United Kingdom. And, still only 60, she doesn’t have to stop there. In five years’ time I can see her becoming the first woman master of the rolls, head of civil justice in England and Wales.

But I must stop making predictions: most of my recent ones have been wrong. I simply didn’t imagine that Rose, who had been in the Court of Appeal for less than two years when Lady Black retired early from the Supreme Court, would get the promotion over the heads of so many colleagues. The guessing game was easier when the judiciary was more hierarchical and appointments depended on being well known to the lord chancellor.

“In the days when shoulders had to be ‘tapped’, my shoulder wouldn’t have come to anybody’s attention for tapping,” she told Inglese in 2015. “The current transparent system acknowledges that some people with exceptional legal skills may have chosen to use them in a different legal context. For me, the turning point was the influential work of the late Dame Juliet Wheldon (when Treasury Solicitor around the turn of the century) to make government lawyers eligible for senior judicial posts. When I left chambers in 1995, my one regret was that I would never be able to be a judge. Once the position changed, I knew I really wanted to be in the High Court and I don’t mind saying that I planned carefully how to get there.”

Lord Reed, president of the Supreme Court, said that he and his fellow justices looked forward to welcoming Rose to the court next month:

Having spent a substantial part of her career working in government and parliament, Lady Justice Rose will add significantly to the diversity of experience on the court. Her outstanding legal ability and breadth of experience will be invaluable in maintaining the high quality of our judgments and our reputation as an international centre of legal excellence.

He’s right. Diversity of experience is the most important diversity of all.