The legacy of beloved singing cowboy Roy Rogers has been tarnished by revelations in a new book about porn star-turned-feminist Linda Lovelace.

In Inside Linda Lovelace's Deep Throat, author Darwin Porter has uncovered the truth behind the hooker and X-rated star's celebrity conquests, detailing alleged sexy romps with Frank Sinatra, Paul Newman, Johnny Carson and even Katharine Hepburn.

But it's a one-night tryst with kinky Rogers that'll shock most readers.

Porter claims movie horse Trigger's best pal booked Lovelace for a threesome with a Las Vegas showgirl when he was in his 60s.

The author alleges family man Rogers had a dark side that "came out on his secret visits to Las Vegas, where he patronised hookers" and enjoyed kinky sex he didn't get at home.

According to Porter, he paid Lovelace $300 (£188) to let him "whoop my butt real hard" - and he gave her priceless showbiz titbit too, revealing he had bedded Marilyn Monroe in 1946 when she was a young hopeful called Norma Jean Baker.