She added: “Philip confided in his brother-who-never-was, David Milford Haven, that Lilibet had a very healthy appetite sexually.
“He also let slip to his other Mountbatten cousin, Patricia, that Lilibet had the most beautiful skin all over.
“There has never been any doubt that they had a torrid time between the sheets. It started in her marriage and continued throughout, and there was never any secret about it.
“Philip himself said she was a goer and in civilised circles an appreciation of sex has never been regarded as shameful but a sign of good health.”
Lady Colin stands by her book despite being branded “tawdry”.
“What I have written stands the test of time and if it’s going to come out it may as well come out through somebody who is even-handed and balanced, and has no anti-Monarchist agenda.”