Groep 1850 (also known as Group 1850) was a Dutch psychedelic rock band that was founded in 1964 in The Hague. The band, despite never achieving success outside the Netherlands, are now considered one of the most innovative acid rock bands from the era. The band disbanded soon afterwards, but was sporadically active through the 1970s. Especially notable was another single, 1971's "Fire" / "Have You Ever Heard?", which appeared on Polydor. In subsequent years related albums have appeared by S.I.X. (Sjardin's Invisible X-factor), Sjardin's Terrible Surprise and Orange Upstairs.