Catherine Duchess of Cambridge and Prince William leaving hospital with their newborn baby boy. Photo by Tim Rooke/REX/Shutterstock (9639909cg)

Prince Charles is in full grandfather mode — corny jokes and all.

On Monday, the 69-year-old welcomed another grandchild when his daughter-in-law, the Duchess of Cambridge, Catherine Middleton, gave birth to her third child.

The newborn, who weighed 3.8 kilograms, is 5th in line to the throne following the implementation of the Succession to the Crown Act in 2015.

In an official announcement released by Clarence House, the Prince of Wales joked that he does not know how he will be able to keep up with all his grandchildren.

And this is before Prince Harry and Meghan Markle have had any of their own!