Answer by taking a quote from the following article:

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.

Reported difficulties among band members saw a split during the recording of Bedlam Born. Woods reportedly was uncomfortable with the financial arrangements of the band, health problems forced Johnson into retirement, and drummer Dave Mattacks' period as an unofficial member came to an end during this time.  For a while the band consisted of just Peter Knight and Tim Harries, plus various guest musicians, as they fulfilled live commitments. Rick Kemp resumed playing with the band at some of these gigs, with Harries switching to lead guitar. This was an uncertain time for the future of the band, and when Harries announced he was not keen to continue his role, even the willingness of Kemp to return to the line-up full-time was not enough to prevent what was effectively a break-up.  In 2002, Steeleye Span reformed with a "classic" line-up (including Prior), bringing an end to the uncertainty of the previous couple of years. Knight hosted a poll on his website, asking the band's fans which Steeleye songs they would most want to see the band re-record. Armed with the results, Knight persuaded Prior and Genockey to rejoin, coaxed Johnson out of a health-induced retirement, and along with Kemp and Knight, they released Present--The Very Best of Steeleye Span (2002), a 2-disc set of new recordings of the songs.  But Bob Johnson's health prevented him from playing live shortly before the 2002 comeback tour, and he was replaced at the eleventh hour on guitar by Ken Nicol, formerly of the Albion Band. Nicol had been talking with Rick Kemp about forming a band when Kemp invited him to play for the tour, and this was to herald a significant return to form for the band.

why did Steeleye Span break up?
financial arrangements of the band, health problems