A BBC article in 1981 suggested the cause of this was most likely because of nerves. “Wedding day nerves were apparent during the ceremony,” it read. “Diana mixed up the prince’s names, calling him Philip Charles Arthur George, rather than Charles Philip.”

       Royal biographer Andrew Morton’s 1983 book “Andrew: the Playboy Prince” takes a look at the historic wedding day.

       Mr. Morton suggests Prince Andrew teased Princess Diana about the situation during the reception.

       “At the Buckingham Palace reception afterwards, clown prince Andrew was on his best form, teasing his new sister-in-law and telling the new Princess of Wales: You married my father.”

       The author also revealed the first ever balcony kiss for a royal wedding by Charles and Diana was Prince Andrew’s idea.

       Mr Morton said: “As bride and groom waved happily to the hundreds of thousands thronging outside the Palace, Andrew urged Charles: 'Go on, give her a kiss.’ Big brother obliged, to the delight of the nation.”

       Diana also modified their wedding vows by removing the word “obey” her husband.

       Kate Middleton omitted the same word during her wedding ceremony to Prince William in 2011.

       The Prince of Wales and Diana’s wedding was referred to as the wedding of the century as 750 million watched the royal wedding back in 1981.

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       Over 600,000 people lined the streets to get a glimpse of the royal bride.

       Princess Diana’s wedding dress was designed by David and Elizabeth Emanuel.

       David told Woman’s Own: “Diana rang up like anybody else and made an appointment to try my dress designs.

       “The thing about that dress was, it had to be young, it had to be pretty. She was going in as Lady Diana Spencer, but coming out as the Princess of Wales.”

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       The wedding dress is currently on display at Kensington Palace.