Background: Steeleye Span are an English folk rock band formed in 1969. Still active today, along with Fairport Convention, they are amongst the best known acts of the British folk revival, and were among the most commercially successful, thanks to their hit singles "Gaudete" and "All Around My Hat". They had four Top 40 albums and achieved a certified gold record with sales of "All Around My Hat". Throughout their history, Steeleye Span have seen many personnel changes.
Context: In 1995, almost all the past and present members of the band reunited for a concert to celebrate the 25th Anniversary of the band (which would later be released as The Journey). The only former members not present were founding member Terry Woods, Mark Williamson, and Chris Staines.  A by-product of this gig was founding vocalist Gay Woods rejoining the band full-time, partly because Prior was experiencing vocal problems, and for a while Steeleye toured with two female singers, and released the album Time 1996, their first new studio album in seven years.  There were doubts over the future of the band when Prior announced her departure in 1997, but Steeleye continued in a more productive vein than for many years, with Woods as lead singer, releasing Horkstow Grange (1998), and then Bedlam Born (2000). Fans of Steeleye's "rock" element felt that Horkstow Grange was too quiet and folk-oriented, while fans of the band's "folk" element complained that Bedlam Born was too rock-heavy. Woods received considerable criticism from fans, many of whom did not realise that she was one of the founding members and who compared her singing style unfavourably to Prior's. There was also disagreement among the band about what material to perform; Woods advocated performing old favourites such as "All Around My Hat" and "Alison Gross", while Johnson favoured a set that emphasised their newer material.  Liam Genockey had also left the band in 1997, and on these albums the drum kit was manned by Dave Mattacks, who was not an official member of the band.
Question: why did they leave?. Whats the answer?
Liam Genockey had also left the band in 1997, and on these albums the drum kit was manned by Dave Mattacks, who was not an official member of the band.