Original: As a psychedelic band led by Syd Barrett in the late 1960s , Pink Floyd had moderate mainstream success and were one of the most popular bands in the London underground music scene ; The UFO club , Pink Floyd however , Barrett 's erratic behavior eventually forced his colleagues to replace him with guitarist and singer David Gilmour .
Simplified: Pink Floyd had moderate mainstream success and were one of the most popular bands in the London underground music scene in the late 1960s led by Syd Barrett ; however , Barretts decline in health would eventually forced his band members to replace him with guitarist and singer David Gilmour .