Keef Hartley worked with what English musician and vocalist born in Liverpool in 1938?
Keef Hartley Keith "Keef" Hartley (8 April 1944 – 26 November 2011) was an English drummer and bandleader. He fronted his own eponymous band, known as the Keef Hartley Band or Keef Hartley's Big Band, and played at Woodstock. He was later a member of Dog Soldier, and variously worked with Rory Storm, The Artwoods and John Mayall.
Freddie Mercury Farrokh "Freddie" Mercury (born Bulsara; 5 September 1946 – 24 November 1991) was a British singer, songwriter and record producer, known as the lead vocalist of the rock band Queen. He was known for his flamboyant stage persona and four-octave vocal range. Mercury wrote numerous hits for Queen, including "Bohemian Rhapsody", "Killer Queen", "Somebody to Love", "Don't Stop Me Now", "Crazy Little Thing Called Love", and "We Are the Champions". He led a solo career while performing with Queen, and occasionally served as a producer and guest musician for other artists.