Those who enjoyed the TV series The Crown will enjoy this entertaining and well-researched book which fills in the background to centuries of arranged royal marriages and the arcane rules that governed them. For centuries marriages of princes could only take place to virginal Protestant princesses. Most were unhappy, royal wives were seen as baby factories (as Princess Diana observed). What mattered was the virginity of the bride so that she did not go to the altar bearing another man's child who would inherit The Crown, the symbol of hereditary monarchy.

Most kings and princes took mistresses - or, in the cases of King Edward II and James I, male lovers - while siring sons by their wives to continue the royal line of Tudors, Stuarts, and Hanoverians who when fighting the Germans changed their name to Windsor.

Queen Elizabeth II, as head of the Anglican Church, had the difficult task of denying her sister, Princess Margaret, the right to marry the divorced war hero she loved. Prince Charles having seen his uncle abdicate because he could not marry an American divorcee, knew proposing to Camilla who lacked a title was impossible. His tragic mismatch to the virginal teenage Lady Diana Spencer ended in Camillagate and other scandals. After Diana's tragic death, after ignoring Camilla who was living with Charles the Queen allowed her heir to marry the woman he loved as crowning a king with a mistress would have been impossible.

The Queen's grandsons were also allowed to marry for love. Kate Middleton, wife of Prince William has adapted brilliantly to royal duties combined with motherhood and the public believe she will make an admirable queen. Prince Harry's love match to a divorced bi-racial American actress would have had his royal ancestors turning in their graves, but stylish hard working Meghan Markle has proved herself so popular in her role as Duchess of Sussex beside her husband the Queen has commended her.