[PAR] [TLE] Deep Purple [SEP] Deep Purple are an English rock band formed in Hertford in 1968.  The band is considered to be among the pioneers of heavy metal and modern hard rock, although their musical approach changed over the years.  Originally formed as a progressive rock band, the band shifted to a heavier sound in 1970.  Deep Purple, together with Led Zeppelin and Black Sabbath, have been referred to as the "unholy trinity of British hard rock and heavy metal in the early to mid-seventies".  They were listed in the 1975 "Guinness Book of World Records" as "the globe's loudest band" for a 1972 concert at London's Rainbow Theatre, and have sold over 100 million albums worldwide. [PAR] [TLE] Born Again (Black Sabbath album) [SEP] Born Again is the eleventh studio album by English heavy metal band Black Sabbath, released in August 1983.  It is the only album the group recorded with lead vocalist Ian Gillan, best known for his work with Deep Purple.  It was also the last Black Sabbath album for nine years to feature original bassist Geezer Butler, and drummer Bill Ward, until he played the studio tracks on their 1998 live album "Reunion".  The album has received mixed to negative reviews from critics, but it was a commercial success upon its 1983 release, reaching No. 4 in the UK charts.  The album also hit the top 40 in the United States.
[PAR] [TLE] Deep Purple [ SEP ] Deep Purple are an English rock band formed in Hertford in 1968 . The band is considered to be among the pioneers of heavy metal and modern hard rock , although their musical approach changed over the years . Originally formed as a progressive rock band , the band shifted to a heavier sound in 1970 . Deep Purple , together with Led Zeppelin and Black Sabbath , have been referred to as the " unholy trinity of British hard rock and heavy metal in the early to mid - seventies " . They were listed in the 1975 " Guinness Book of World Records " as " the globe 's loudest band " for a 1972 concert at London 's Rainbow Theatre , and have sold over 100 million albums worldwide . [PAR] [TLE] Born Again ( Black Sabbath album ) [ SEP ] Born Again is the eleventh studio album by English heavy metal band Black Sabbath , released in August 1983 . It is the only album the group recorded with lead vocalist Ian Gillan , best known for his work with Deep Purple . It was also the last Black Sabbath album for nine years to feature original bassist Geezer Butler , and drummer Bill Ward , until he played the studio tracks on their 1998 live album " Reunion " . The album has received mixed to negative reviews from critics , but it was a commercial success upon its 1983 release , reaching No . 4 in the UK charts . The album also hit the top 40 in the United States .
In which year, was this English rock band formed in Hertford that the lead vocalist Ian Gillan of Sabbath is best known for collaborating with?
In which year , was this English rock band formed in Hertford that the lead vocalist Ian Gillan of Sabbath is best known for collaborating with ?
1968
1968