Baccara was a Spanish duo (Mayte Mateos and María Mendiola) who worked as dancers/singers in a hotel in the Canary Islands. German producer Ralf Siegel heard them singing and composed "Yes Sir, I Can Boogie" especially for them in 1977. It was the first single of their career, #1 in the United Kingdom (first Spanish artist to achieve this), #1 in several European countries and sold more than 16 million copies worldwide.
@UKBackintheDay2 This is the wrong track. Their response track was "Their Law" from the album "music for the jilted generation" which has an excellent pictorial on the limited edition sleeve notes.