Why Zara Tindall isn't a princess but her younger cousins Beatrice and Eugenie are

The Queen and Prince Philip have a large family around them to keep them busy and help out with royal duties.

They have five children, eight grandchildren, seven great-grandchildren and another one on the way .

Some are full-time working royals but those further down the line of succession lead much more normal lives and many of them don't even have titles.

While most of the titles are quite straightforward - there is one question many people often ask about the Queen's granddaughters.

Beatrice and Eugenie became princesses when they were born, but their older cousin Zara didn't - even though they have the same relationship with the Queen.

Princess Eugenie joined the Queen for the Royal Maundy Service on Thursday (Tim Rooke/REX)

Queen beams as Princess Eugenie joins her at Windsor Castle Maundy service  

All of the monarch's children were given titles when they were born, and she offered them the opportunity to also hand them to their children as well.

Princes Charles and Andrew accepted the offer, meaning William, Harry, Eugenie and Beatrice became princes and princesses - but Anne refused.

Even though she was the Queen and Philip's second child, she was knocked down the line of succession when her brothers were born.

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She knew that by the time her children were born they would very low down on the list for the throne, so she wanted them to have normal lives.

This is a decision Zara is very grateful for.

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Speaking in 2015 she said: "I'm very lucky that both my parents decided to not use the title and we grew up and did all the things that gave us the opportunity to do."

Zara is a top equestrian and won a silver medal at the 2012 Olympic Games in London.

She is married to rugby player Mike Tindall and the couple have two children, who are also without titles.

While the Duke and Duchess of Cambridge's children George, Charlotte and Louis were all given prince or princess titles, it is unlikely that Meghan Markle and Prince Harry will make their little one a HRH.