The Wales family stole the hearts of the nation as they took part in the Big Help Out for the third day of Coronation celebrations.
It was Prince Louis' first ever royal engagement, which he carried out with his older siblings, Prince George and Princess Charlotte.
The scheme was organised by The Together Coalition and partners such as The Scouts, the Royal Voluntary Service and faith groups from across the United Kingdom.
Some 55,123 events were due to take place, created by 33,228 grassroots and community organisations.
In a "family day out volunteering", George, nine, Charlotte, eight, and Louis, five, helped renovate a Scout hut in Slough, Berkshire, under the watchful eye of their parents William and Kate.
Louis joined his siblings and parents by shovelling dirt, pushing wheelbarrows and operating a digger.
Here we take a look at some of the most adorable moments of the day...
Louis' reaction to treat
After the hard work was over, the Wales family tucked into a sweet treat around the fire - and it's safe to say Louis enjoyed getting his chops around a s'more.
Kate and a scout member helped the five-year-old prepare a marshmallow biscuit sandwich, which he really could not wait to devour.
The little Prince didn't waste a second getting the sticky s'more into his mouth and licked the marshmallow off his fingers before tucking in.
In the background, William joked about his youngest son: "You won't hear a peep out of him now", which got the crowd chuckling.
After Louis' first bite, he turned around and rolled his head backwards in delight, before falling onto his sister Charlotte.
George and Louis try their hand at digging
William sat nine-year-old George on his lap as he took control of a digger and dumped a bucket full of earth onto a spoil heap.
After seeing George have a go, Louis turned to his mum Kate and said: "I want to go in with him".
Louis was then given his chance to take charge and asked "What does this one do?" as he pulled a lever.
But he was not phased when the digger lurched back slightly and was encouraged by his father, who said "Keep going Louis, that's it".
Later, the five-year-old prince was given the task of filling a wheelbarrow with builders' sand and he focused on the job, diligently shovelling the material before wheeling the barrow himself.
Kate watched over her son, telling him to shovel in a "bit more" and when the barrow was a quarter full, Louis wheeled it away to help volunteers building a path and made a number of runs.
Charlotte's big sister warning
The young royals beavered away helping to renovate the 3rd Upton Scouts Hut.
Meanwhile, the adults reset a path, dug a new soakaway, sanded and revarnished a door, screwed together planters and created a mural as a lasting legacy of their work.
Louis and Charlotte, aged eight, painted the brick base of a planter with masonry paint and as the young prince sploshed it about, his sister told him: "You've got paint in your hair! Louis, look at me! Look at me!"
The five-year-old carried on regardless and his sister added: "You've got to wipe it."
Louis' plans for the future
The young prince revealed a sweet plan to follow in his dad and grandad's footsteps when he grows up.
One volunteer asked Louis: "You might want to be a painter when you grow up?"
"No a fighter pilot," he responded.
"Just like your father and grandfather!" the lady replied.
William's concerns about school run
The Prince of Wales revealed his concerns about getting the kids up early for the school run on Tuesday.
William told one volunteer that his children were "so tired" after the Coronation festivities, reported the Daily Mail.
He also expressed concerns over having trouble getting them up for school the following day.
The Wales family have had an extremely busy last few days, playing huge roles in the Coronation ceremony, appearing on Buckingham Palace's balcony, going on walkabouts and staying up late for the Coronation Concert.
Louis' cute nickname
Another never-before-heard detail that Kate let slipped while volunteering is Louis' secret - yet very adorable - nickname.
As she supervised as the young prince, she told him to throw his empty stick from toasting marshmallows into the fire, revealing his alternative moniker - Lou Bugs.
And his hard work was rewarded as he was later presented with a sweet treat.
Kensington Palace described the event as Louis' first royal engagement.
Although he has attended a number or high-profile royal events it is thought the Slough visit was the first time the prince has actively engaged with the public.
Charlotte's archery skills
The three young royals took part in a game of archery which brought out the competitive spirit in the siblings, and later the family were presented with Scout scarves.
Scout member Milena Pereira said about the archery: "Charlotte mentioned she has done it before at home, but they were all determined to have a go.
"They were really nice and respectful, a nice family, so today was a nice surprise, we didn't know they were coming."
