The Chelsea F.C. is Irish.
The 1954 -- 55 season was Chelsea Football Club 's 50th of competitive football , their Golden Jubilee and their 20th consecutive year in the English top flight . Chelsea Football Club ( [ ˈtʃɛlsiː ] ) is an English professional football club based in Fulham , London , that competes in the Premier League , of which they are reigning champions . Chelsea had their first major success in 1955 , when they won the league championship .