I don't want to be overly critical of this book, although there is a certain temptation. What you have here is a very detailed (sometimes too much so!), often charming description of Veronica Maclean's life, which certainly provides interesting insights into a world that most mere mortals will never even glimpse, if indeed it even exists today.
What sometimes bothered me, however, was a tendency on the part of Mrs Maclean to take her immensely privileged upbringing and lifestyle for granted. It is only on the very last page of the book that she finally acknowledges how fortunate she has been, prior to which she seems to find a childhood spent in castles and the drawing room banter of the English nobility to be par for the course. Although I do not for a moment doubt her integrity, and she comes across as absolutely charming, there are moments when you can't help getting the feeling that she is sometimes a bit detached from reality in a Marie Antoinette kind of way, and this grated with me a little.
The other problem - and this is a problem of the reader, not the author - is the potential trap of reading the book in search of Fitzroy Maclean. I make no secret of the fact that this was one of the main reasons for my buying the book, yet the potential reader should be aware that Veronica Maclean sticks to her mandate of writing HER autobiography, and Fitzroy does not pop up until well past the halfway mark, prior to which you will have to grapple with lengthy descriptions of Mrs Maclean's ancestors and their role in Scottish history. This is not a criticism as such, but I think the reader should be aware that this is unquestionably a book about her, not him.
In a similar vein, although famous individuals tantalisingly flow in and out of the narrative, there is a lack - perhaps deliberate/discreet - of the telling insights one would hope for from someone who was fortunate enough to get to know personalities as diverse as Belloc, Churchill, Kennedy or Tito.
So, overall, there is certainly nothing to be lost from reading this book, but it is not what I would call essential reading.