Top secret: the Queen's dress size A new book reveals the secrets of Her Majesty the Queen's wardrobe - corgis included - but don't expect to learn her clothes size. A new book reveals that the only observers privy to a fitting session with Her Majesty the Queen are Angela Kelly, her personal assistant, adviser and curator; her dressmaker, and a couple of her furry friends. Kelly, author of Dressing The Queen: The Royal Wardrobe , has worked in the Royal Household for nearly 20 years, rising from the role of dresser to managing Her Majesty's entire wardrobe. IN PICTURES: 60 years of the Queen's fashion hits "Often we are joined by one or two of the Queen's corgis who like to keep a watchful eye over things!" she writes of a fitting session, which typically takes half a day. "Otherwise, as with any fitting session, these are very private and we are the only people present," Kelly adds. The book chronicles the meticulous planning of the monarch's outfits - fabric research for this year's Diamond Jubilee celebrations began two years earlier - and the thought processes given to colour schemes, hat sizes and weights of handbags. IN PICTURES: Queen Elizabeth II's best accessories "For Her Majesty, each of the four seasons is equally important and must therefore be considered separately and individually" says the book, while pointing out that mainstream designers' approach to the seasons with spring/summer autumn/winter collections just wouldn't cut it for HM. READ: 60 years of Queen Elizabeth's impeccable style Other facts reveal how after 6pm the Queen does not usually wear a hat but may revert to a headpiece or for evening state banquets, a tiara, and that when visiting schoolchildren, Her Majesty will favour an outfit that features feathers, twirls, twists and flowers to "hold their attention." A generous dresser, the Queen has in turn helped advise her staff on what works and what doesn't in the wardrobe department; squeezing fabrics to see if they remain creased is one of the best tips she has dispensed to Kelly, while her frugality means she embraces using old fabrics from the "stockroom." One fact the book doesn't reveal, however, is the Queen's dress size. Her Majesty "likes her clothes to be fitted but not too tight" is as close as Kelly gets to describing our monarch's shape.