Who sang backup for Joe Cocker at Woodstock in 1969?

At Woodstock in 1969, the backup singers for Joe Cocker were known as The Grease Band. They provided vocal support and harmonies for Cocker's iconic performance of songs like "With a Little Help from My Friends." The Grease Band consisted of musicians such as Chris Stainton, Alan Spenner, and Henry McCullough, who contributed to the overall sound and energy of the performance.