BLISTERING BARNACLES! Is it really 75 years since Tintin, the intrepid boy reporter with the plus-fours and windswept quiff, made his first appearance in a Belgian Catholic newspaper? On a trip to the Soviet Union the fresh-faced correspondent was denounced by the Communist Party and chased by the secret police.

Since 1929, in 22 further adventures, the ginger-haired journalist has been as far afield as the jungles of the Congo, the backstreets of Shanghai, the docks of Chicago and even the surface of the moon 15 years before Neil Armstrong.

In battling baddies alongside his pals Snowy the Dog, the drunken seadog Captain Haddock, Professor Calculus, and those bumbling detectives Thomson & Thompson, Tintin has also sold nearly 200 million books in more than 50 languages and become a merchandising goldmine.

His homeland, having already honoured him with a stamp, has now marked his 75th anniversary with a new euro coin. Exhibitions are touring Spain and the Netherlands, an unfinished final adventure is being published, and a stage production of The Castafiore Emerald episode is playing to packed houses outside Brussels.

He’s also celebrating his 75th birthday in London with a new exhibition at the National Maritime Museum featuring artwork, early sketches and sources of inspiration for his nautical adventures. It’s an appropriate venue because, while Tintin travelled the world, his creator Hergé (born Georges Rémi in 1907) did most of his travelling in the Cinquentenaire Museum near his home in the east of Brussels.

It was a storehouse for shrunken heads, Easter Island statues and whatever else had been hoovered up, in indiscriminate European fashion, by colonial adventurers. They would furnish Tintin’s globe-trotting adventures with a backdrop of amazing detail.

“He was obsessive about accuracy,” says Kristian Martin, the curator of the Maritime Museum’s show. “There’s a night sky in one cartoon in which every star is correctly placed. He studied ship models, sea charts and all kinds of objects to get the details correct.”

Hergé’s lavish frames seem to have complete universes crammed into them (just look at the aquatic underworld in Red Rackham’s Treasure): the cars, ships, trains, planes and rocket to the moon that invite you to relish the ingenious mechanisms that make them go and the thrill of locomotion, preferably at top speed.

Most of Hergé’s characters were drawn from real people. Tintin was based on Hergé’s younger brother. Only an additional goatee separates Professor Calculus from Professor Auguste Piccard, the Swiss physicist who set records for deep-sea exploration.

As his career developed and his audience grew, Hergé felt a responsibility to be as accurate as possible. Aircraft and train designs moved with the times, as did politics: 1930s fictional Borduria (the enemy of peaceful Syldavia) is run by thinly disguised Nazis; by the Fifties its heavies are more Eastern bloc in style.

He never quite forgave himself for his crude depiction of Russia in Tintin in the Land of the Soviets, part of the anti-communist slant of his paper, nor for the white-man’s-burden attitude toward the natives in Tintin in the Congo.

Thanks to a young Chinese Catholic, Chang Chon-ren, studying at the Brussels Academy of Arts in the 1930s, Hergé saw the evils of imperialism as well as developing a more sophisticated graphic style; Tintin’s adventures began to look more like movie storyboards, alternating the point of view from front to back, shifting from extreme close-ups to long-distance panoramas.

In gratitude, Chang was made a character, Chong-Chen, in The Blue Lotus, which lambasts Japan’s invasion of China at a time when many Europeans favoured the Japanese. King Ottakar’s Sceptre bravely alludes to the Anschluss and Sudetenland on the eve of war.