It turns out, HRH picks outfits to ensure maximum visibility in crowds so that members of the public have a better chance of seeing her.
"She needs to stand out for people to be able to say 'I saw the queen'," the Queen's daughter-in-law Sophie, Countess of Wessex, explained in the new documentary The Queen at 90.
"Don't forget that when she turns up somewhere, the crowds are two, three, four, 10, 15 deep, and someone wants to be able to say they saw a bit of the queen's hat as she went past."
Thankfully, the Queen's favourite nail polish - the only one she has worn for the past 28 years - is a classic light pink shade, which suits any and all bright colours.
