Neville Gwynne is the author of a best-selling grammar book 'Gwynne’s Grammar', modestly entitled 'The Ultimate Introduction to Grammar and the Writing of Good English'. I confess to not having read Mr Gwynne's book, but I think we can get a fairly good idea as to the affable Mr Gwynne's attitude to English in various other ways: from an interview he gave on BBC Radio 5, from a grammar quiz he wrote for the Telegraph newspaper, from the Preface, first two chapters and recommended reading from the book itself, available to read at Amazon; and from various reviews, especially rather a long one in the Telegraph.
While I was reading the preface to his book at Amazon, I came across an apparent distinction between the words gender and sex I had only vaguely heard about before.
