"The Liquidator"

From TheChels.info - The Chelsea Football Club Wiki

"The Liquidator" is an early reggae instrumental released in the United Kingdom by the Harry J Allstars in 1969. Its association with Chelsea dates from this time, when contemporary chart hits were regularly played at the ground, and it proved popular with the fans. In recent years it has been reintroduced as the tune that the teams run out to at Stamford Bridge. The tune is also popular with fans of West Bromwich Albion, Wolverhampton Wanderers and Wycombe Wanderers.

Having been played at Chelsea in the late 1960s shortly after the tune began to be played in London clubs, it has been an "official" Chelsea song since 1970, when the matchday programme gave away copies as competition prizes.[1]

"Way back in 1969, supporters of the Chelsea football team revered players such as Bonetti, Osgood and Hollins. The boys performed under the watchful eye of manager Dave Sexton to the tune of Harry J & All Stars chartbuster, 'The Liquidator'. Whether the tune helped the squad in their successful 1970 FA Cup campaign and subsequent Cup Winners Cup victory we shall never know. One thing is certain the theme to those victories was undoubtedly 'The Liquidator', with its Hammond organ crescendos that lead to the chant of "CHEL-SEA!"."

- Liner notes in "Liquidator - The Best of the Harry J All Stars".

There is crowd participation at regular intervals during the tune with four claps and a shout of "Chelsea!" repeated:

clap, clap, clap, clap,

Chelsea!

clap, clap, clap, clap,

Chelsea!

clap, clap, clap, clap,

Chelsea!