"He was with us for an hour and a half," an insider at Uppercuts salon in Brighton, East Sussex, said. "He had both a cut and some brown coloring added. It is not that unusual. Despite his age he still has a fine head of hair."
The 61-year-old McCartney's makeover cost around $100.
Following his appointment, McCartney's wife, Heather Mills McCartney, 36, drove by to pick up the famed singer.
"He was keen for Heather to have a look, so he ran over to show off his new (look)," an onlooker said.
McCartney and his wife have an infant daughter, Beatrice, who was born in October.