Royal author Penny Junor wrote about its use in her 2005 book ‘The Firm’: “It is not quite the Orient Express, as most of the coaches are 30 to 35 years old and could do with refurbishment, but the train is extremely comfortable by any standards.“
“It is a home from home, and one of the most secure ways of accommodating the Royal Family overnight.
“Both the Prince of Wales’ and the Queen’s coaches are heavily reinforced; they are ten times heavier than the other coaches.”
Captain Tim Hewlett who once stood as the Queen’s Senior Air Equerry, has also stated security is one of the main costs of the royal train.
source: express.co.uk