Zara Tindall may be devoted to all things horses, but one decision during her appearances at Royal Ascot this week has caught attention online. The Princess Royal's daughter has joined King Charles, Queen Camilla and other members of the Royal Family for every day of the annual event in Berkshire so far this week.

While that has been Zara's married name since her wedding to Mike Tindall in 2011, it appears that it is against tradition.

In its first edition of Correct Form in 1970, Debrett's noted that a married woman using her own Christian name or initials "implies that her marriage was dissolved" and that "this mistake is frequently made".

By 1976, Correct Form added a footnote that read: "Ladies, especially those engaged in business or the professions, who prefer not to disclose their marital status, have recently taken to using the prefix 'Ms'" but urged readers not to use it "unless a lady has indicated this preference, because it offends many more than it pleases".

While Zara Tindall's badge refers to her as Mrs Zara Tindall, rather than Mrs Mike Tindall, other senior female guests have opted for the traditional method.

Much like Harriet Phillips, the Princess of Wales's mother, Carole Middleton and her sister-in-law, Alizee Thevenet, wore badges featuring the names "Mrs Michael Middleton" and "Mrs James Middleton".

However, in the years that have followed, Debrett's now refuses to say whether either form of address is right or wrong. “Traditionally, it is considered incorrect for a married woman or a widow to be addressed by her own forename or initials, as this implies that her marriage has been dissolved," it says.

"However, it is becoming increasingly customary for married women and widows to use their own forenames and initials."