Beaming up at his mum with a super-cute toothy grin, Louis looks very chuffed with his adventurous efforts.
A second snap show's the fifth in line to the throne sitting atop a moss-covered stone wall, once again showing off that cheeky grin and grass-smothered jumper.
“He really is the most cheerful, smiley little boy,” a source told PEOPLE. “He’s always so happy and content.”
Months earlier, Kate commented on Louis' ability to crawl at high speeds.
Happy birthday for April 23, little Louis!
WATCH: LITTLE LOUIS' SPECIAL DAY