After that the group lasted another four years, although there was a gradual decline in their status and commercial success after 1970. Joe Boyd, whose skillful handling of the band had contributed much to their international success, stopped managing them and returned to the US. The group left Elektra Records and signed with Island, for whom they recorded five albums. The first was a soundtrack to the "Be Glad..." film, and this was followed by the eclectic Liquid Acrobat as Regards the Air, regarded as their best album for some time.  The band continued to tour and record. Rose Simpson left in 1971 and was replaced by Malcolm Le Maistre, formerly of the Stone Monkey troupe. Mike Heron took time out to record a well-received solo album, Smiling Men with Bad Reputations, which, in contrast to the ISB's self-contained productions, featured a host of session guests, among them Pete Townshend, Ronnie Lane, Keith Moon, John Cale and Richard Thompson. The following year, Licorice left, and was replaced by Gerard Dott, an Edinburgh jazz musician and friend of both Heron and Williamson who had contributed to Smiling Men. Williamson also recorded a solo album, Myrrh, which featured some of his most extraordinary vocal performances.  The group's changing lineup, adding Stan Schnier (aka "Stan Lee") on bass, Jack Ingram on drums, and Graham Forbes on electric guitar reflected moves toward a more conventional amplified rock group. Their final albums for Island were received disappointingly, and the label dropped them in 1974. By then, disagreements between Williamson and Heron about musical policy had become irreconcilable, and they split up in October 1974.

Answer this question "what else happened between 1971 and 1974?" by extracting the answer from the text above.
Mike Heron took time out to record a well-received solo album,