"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 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

Mike Tindall has given a unique insight into his close bond with Princess Anne - including what he calls his mother-in-law behind closed doors. The former rugby professional married Zara Tindall - who is Princess Anne 's only daughter - back in 2011. The pair, who met in 2003, now share three children - Mia, 10, Lena, six, and three-year-old Lucas.