"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.
Justin Bieber crashes Drake Bell's album release party
Chipotle plans first price increase in 3 years