"M'am, not Mum!" said the retired rugby star, who is married to the Princess Royal's daughter, Zara Mike Tindall knows just what to call his royal mother-in-law, Princess Anne. On Nov. 4, the retired rugby star made the revelation while appearing on Good Morning Britain to discuss his new book,

Mother-in-laws can sometimes be tricky to deal with - and worrying about how they may react might be amplified if they're a princess.

Mike Tindall has highlighted the special roles that Princess Kate, Prince William and Princess Anne hold in the world of rugby. The former England international rugby player who is married to Princess Anne's daughter Zara Tindall has a strong bond with the senior members of the Royal Family.

Mike Tindall has been part of the Royal Family for over a decade after marrying Zara Tindall in 2011 and he has now revealed how he addresses his mother-in-law Princess Anne in private

Former rugby player Mike Tindall appeared on Good Morning Britain with James Haskell to chat about their new book The Good, the Bad and the Rugby - Unleashed

Mike Tindall keeps things formal with his mother-in-law Princess Anne. The former England rugby star - who has been married to King Charles' niece Zara Tindall since 2011 - was asked how he addresses the Princess Royal in private and he admitted it isn't any different to the way other people speak to her in public.