Premise: Pink Floyd . Guitarist and vocalist David Gilmour joined in December 1967 ; Barrett left in April 1968 due to deteriorating mental health . Syd Barrett . Best known as a founder member of the band Pink Floyd , Barrett was the lead singer , guitarist and principal songwriter in its early years and is credited with naming the band . Barrett was excluded from Pink Floyd in April 1968 after David Gilmour took over as their new guitarist , and was briefly hospitalised amid speculation of mental illness .
Hypothesis: Pink Floyd has a member called David Gilmour.
Label: ENTAILMENT