Both, of course, wrote and sang their own compositions.
But while the duo were prolific it was never a comfortable relationship. According to Boyd, who was, by this time their manager and producer and was, therefore, aware of the internal dynamics “Neither would agree to the inclusion of a new song by the other unless he could impose himself on it by arranging the instruments and working out all the harmonies.” (White Bicycles p. 186)
Williamson’s girlfriend Licorice appeared on 5000 Spirits on vocals and percussion with the peerless Danny Thompson handling bass duties, but when Williamson suggested Licorice become a permanent member of the band Heron insisted his girlfriend, Rose Simpson join as well, bought er an electric bass and taught her how to play the required parts by rote.
A short tour of the UK supporting Elektra acts Tom Paxton and Judy Collins, regular gigs at London clubs including Les Cousins, the UFO Club (co-owned by Boyd) and the Speakeasy along with a spot on the bill along with Joni Mitchell and Leonard Cohen at the Newport Folk Festival, on a bill spread the word. Enthusiastic reviews in the music press and exposure on John Peel's pirate Radio London Perfumed Garden radio show and subsequently on Peel’s BBC show (Top Gear) maintained the momentum.
The 5000 Spirits album went to Number One in the UK folk chart. Hangman's reached the top 5 in theBritish album charts and was nominated for a Grammy in the USA.
By 1968, the group were playing (and filling) venues like London’s Royal Festival Hall and Royal Albert Hall, and picking up gigs at open-air festivals and prestigious Stateside rock venues including both of Bill Graham’s Fillmore auditoriums.
Boyd made the mistake of introducing them to David Simons (aka "Rex Rakish” from Jim Kweskin's Jug Band) after an appearance at the Fillmore East in New York and remarking that he’d straightened his act up considerably. The change was attributed to Scientology, and when Boyd left them to talk Simons persuaded them to enrol in the cult.
The band's support for Scientology has been used to explain what many fans saw as a gradual decline in the quality of their work, but 1968’s other album Wee Tam and The Big Huge was recorded before the US trip and while it wasn’t quite as groundbreaking as its two predecessors they had to slow down eventually.