You are sending a link to... Stone the Crows - Sad Mary
From their 1970 album Ode to John Law. You don't get many blues/prog rock songs about Mary Queen of Scots.
Maggie Bell vocals, Les Harvey (brother of Alex the sensational, tragically died on stage in 1972 after an electric shock of a dodgy mic) Colin Allen on drums. He and Bell will be touring in the spring with Zoot Money in the British Blues Quintet.