US American rock band active from 1964 to 1999, with several spinoffs, e.g. (1973) or (1976). Despite their British sounding name, they came out of San Antonio, Texas and featured a Tex-Mex sound.

Their most familiar lineup included:
aka Sir Douglas (lead vocals, lead & rhythm guitars, bajo-sexto, fiddle)
Augie Meyers (organ, piano, accordion, guitar, vocals)
Frank Morin (sax, trumpet and keyboards)
Harvey Kagan (bass)
Johnny Perez (drums)

It also included:
Doug "Cosmo" Clifford (drums)
Jack Barber (bass)
Alvin Crow (fiddle, organ, guitar, vocals)
Louie Ortega (guitar, vocals)
Rocky Morales (saxophone, harmonica, vocals)
John "X" Reed (guitar, vocals)
Clay Meyers (drums)
Shawn Sahm (guitar, vocals)
Martin Fierro (various horns)
Bobby Black (pedal steel guitar)
Ernie Durawa (drums)
Mike Buck (drums)
Jon Blondell (bass)
Speedy Sparks (bass)
... and many, many others.