Name the English rock band formed in London who achieved international acclaim with their progressive and psychedelic music and who were a significant influence on the German progressive rock band Sylvan alongside Marillion and Genesis?
Sylvan (band) Sylvan is a German progressive rock band, with some hard rock moments, and some melodic pop-rock elements, showing influences of psychedelic rock, Pink Floyd, Marillion, and Genesis.
If (band) If were a progressive rock band formed in Britain in 1969. Referred to by "Billboard" as "unquestionably the best of the so-called jazz-rock bands", in the period spanning 1970–75, they produced eight studio-recorded albums and did some 17 tours of Europe, the US and Canada.