Who is he?
Lady Nugee is the correct form of address for Emily Nugee (nee Thornbury).
In the context of the Westminster parliament, no one ever referred to Margaret Roberts, or for that matter Constance Gore-Booth**, Nancy Langhorne, Shirley Catlin or Barbara Betts, all of whom subsequently had titles.
** Constance Gore-Booth was the first elected female MP, but in view of her political affiliation never took her seat at Westminster.
But no-one refers to Pritti Sawyer, Liz O'Leary, Esther Davies, Chloe McFadzean, Victoria Kenward, or Lady Lancaster of Kimbolton all of whom serve or have served under Johnson. Claire Perry, who served under Theresa May, took her first husband's surname but not her second, when she remarried.
It should be a woman's right to choose the name she is identified by.
Many women choose to keep their maiden name in their professional life because that is the name they were established by and known by, and I would imagine that the law is one such profession - Lady Hale (who was President of the Supreme Court) did so; the arts certainly is another, it is by no means unknown in education and I would imagine business. It is also helpful if the marriage does not last!
It is rare but not unknown for a man to take his wife's name.
Catlin and Betts were ennobled because of their achievements, not their husband's, and they could, I believe, have chosen the name by which they wished to be identified by in the House of Lords. That is why we have Lord Deben (formerly John Gummer). Working on the same principle, should Thornberry be ennobled in her own right, she could choose the name she is known by.
Gore-Booth and Langhorne were over a hundred years ago, all men and some women had only just been given the vote. Langhorne would have been helped in her campaign by using the name of the previous MP, her husband.
Thatcher may have been known as such but it was her father, not her husband, whose values drove her. The latter was not the world's most successful businessman (walking past his factory and those close by as a child convinced me that I did not want to follow my father and grandfathers into industry).
(In a desperate attempt to link it with the thread title) I wonder whose values Mr Johnson is driven by?
Likewise, the Welsh Parliament don't refer to their Health Minister as Baroness Morgan, though she was already a life peer before seeking election to that legislature.
On the gov.wales website she is referred to as Eluned Morgan, Morgan being her name at birth, not the name of her husband.