LONDON, ENGLAND - JUNE 10: Zara Phillips attends a lunch after the National Service of Thanksgiving as part of the 90th birthday celebrations for The Queen at The Guildhall on June 10, 2016 in London, England. (Photo by Arthur Edwards - WPA Pool/Getty Images)
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LONDON, ENGLAND - JUNE 10: Zara Phillips and Mike Tindall attend a National Service of Thanksgiving as part of the 90th birthday celebrations for The Queen at St Paul's Cathedral on June 10, 2016 in London, England. (Photo by Danny Martindale/WireImage)
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WireImage Danny Martindale

LONDON, ENGLAND - JUNE 10: Zara Phillips and Mike Tindall attend a National Service of Thanksgiving as part of the 90th birthday celebrations for The Queen at St Paul's Cathedral on June 10, 2016 in London, England. (Photo by Danny Martindale/WireImage)
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WireImage Danny Martindale

LONDON, UNITED KINGDOM - JUNE 10: (EMBARGOED FOR PUBLICATION IN UK NEWSPAPERS UNTIL 48 HOURS AFTER CREATE DATE AND TIME) Zara Phillips attends a national service of thanksgiving to mark Queen Elizabeth II's 90th birthday at St Paul's Cathedral on June 10, 2016 in London, England. (Photo by Max Mumby/Indigo/Getty Images)
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