Hence the red and white pole outside of them.

Barbers had the equipment needed for performing bloodletting. Besides cutting hair, they could pull teeth, amputate limbs, and administer leeches. As the barbers knew how to use a razor, it was presumed that they would be skillful in carrying out any treatment that involved cutting the skin, and so the practice was passed over to them.

“The barbers and the surgeons operated in different medical guilds until 1540 when king Henry VIII united the two guilds into one company named ‘The Company of Barber-Surgeons”.
Thevintagenews.com. An excerpt from the original article