United Kingdom, Aug. 16 -- Pierce Brosnan credits "Guinness" for his enviable hair.

The 72-year-old actor explained his dietary theory as to why Irish men have luscious locks when asked how his own mane looks so good and noted that his father Tom "had good hair".

Speaking to Page Six at the premiere of The Thursday Murder Club, Pierce said: "I don't know.

"It's all in the hair, the old Celtic hair."

The former James Bond actor suggested that "potatoes, butter" or "the Guinness" is responsible for the lack of baldness in Irish men of a certain vintage.

When told that he is ageing like fine wine, Brosnan replied: "I'm doing my best!"

Pierce plays retired trade unionist Ron Ritchie in the upcoming Netflix murder mystery film The Thursd...