I was reminded of how worried I was about the breadth of the statutory definition that would apply to anyone holding this office. I remain extremely concerned about it, but at least there is some limit...”

He continued: “I would be much happier if there was a statutory provision that required the Lord Chancellor and therefore the minister to have some legal qualification.”

Supporting mechanisms were also key. “A few years in practice at the Bar in the 1970s tells you very little about the constitutional difficulties, arrangements, dangers and so on that have overtaken your life when you come to be Lord Chancellor at the end of your political career.

That is not directed at Mr Grayling; it is the same with every Lord Chancellor. He needs good legal advisers. I doubt that the Ministry of Justice is filled with lawyers who understand the constitutional subtleties,” he added.

However, “we have the system that we have” and “should keep the Lord Chancellor, provided that we keep him with a heavy department, and provided that he continues to hold by the oath of office that he takes”.

Turning to the role of the Attorney General, which had “assumed greater importance since the constitutional changes”, Lord Judge said: “The objective is to have an individual of impeccable moral courage. The function of the Attorney General is to tell the Prime Minister, the cabinet and for that matter the House of Commons, how he sees it, and that may be diametrically opposed to the views and wishes of those he is advising. So long as he retains this function, and is able to perform it, he is performing a crucial role in our constitution.”

He added that “the last 10 to 12 years or so rather demonstrates that there is no deep political understanding of the niceties of our constitution. I think that [the Lords Constitution Committee] has a heavy responsibility to ensure that someone, at any rate, is made alert to that”.

The committee plans to publish its report in the autumn.