There are at least three bands sharing this name:
(1) Magna Carta was originally formed in London in 10 May 1969 by Chris Simpson (guitar, vocals), Lyell Tranter (guitar, vocals) and Glen Stuart (vocals).
The band are renowned for their gentle ballad style and mythical subject matter. Although never purely a folk band, they managed to successfully bridge the gap between folk and folk rock. The trio released albums for Fontana Records and Vertigo Records, enjoying particular success with 1970s Seasons before Tranter returned to Australia.