United Kingdom, May 18 -- Mike Tindall's dad is a "shell of what he once was" because of Parkinson's Disease.

The former rugby player - who is married to Princess Anne's daughter Zara Tindall - admitted his father Philip is "not doing great" at the moment amid his battle with the degenerative condition, which he was diagnosed with in 2003.

He told Britain's HELLO! magazine: "My dad is not doing great at the moment. Parkinson's is brutal and there is no let up from how it attacks the body and changes people.

"After 23 (plus) years of the disease, it has quite honestly left him a shell of what he once was, which is why I don't want anyone else to see a parent or loved one suffer and have their quality of life decline so massively."

Witn...