Britain’s soft power rubbed off so strongly that one German politician was moved to suggest what might seem unthinkable — injecting some British humour into dry parliamentary proceedings in Berlin.
“We could all take a leaf from that book,” said a beaming Norbert Roettgen, one of many MPs who looked as though they might break into God Save The King after Thursday’s royal address to parliament.
The state visit received wall-to-wall TV coverage in Germany, which has long had a soft spot for British pomp and ceremony — not to mention plenty of time for royal gossip.
The King’s early reign has coincided with a burying of the hatchet after Brexit and the trip was a chance to win back German hearts.
Britain's monarch made numerous foreign visits as Prince of Wales but this was his debut as King — and he proved a potent diplomatic weapon.
On walkabouts, King Charles made time for Union Jack-waving well-wishers who turned out to see him at the Brandenburg Gate in Berlin and during a downpour in Hamburg.
He spoke in German for much of his address in parliament, delivered under a glass dome designed by British architect Norman Foster that is intended to symbolise German unity.
The King's German is not perfect but it is better than many would have managed and the fact he made an effort was noticed and appreciated. Guenter Krings, a conservative MP, was impressed by his “seamless” switching between languages.
Mr Krings said the King’s gestures were “more important than ever” in the post-Brexit world.
“In many respects Britain and Germany have to rebuild their friendly relations which for many decades played out inside the EU,” he said.
The Bundestag laughed as the King reeled off the greatest hits of Anglo-German culture, from The Beatles performing in Hamburg to the comedy acts of Henning Wehn.
The biggest laugh was for an obscure British sketch called Dinner for One that is broadcast every New Year’s Eve in Germany – another well-aimed line that showed the palace had done its homework.
“For the last 50 years we have laughed together ― both at each other, and with each other,” the King said.
MPs applauded as the King praised Germany’s support for Ukraine and its action to tackle climate change.
A shout-out to Hamburg’s green ambitions delighted the city’s former mayor, Chancellor Olaf Scholz — who rarely gets to hear his foreign policy described as “remarkably courageous, important and appreciated” in this chamber.
A boat trip on Friday to the planned Hamburg hydrogen hub, which last year received a first shipment of ammonia from the UAE, gave it a quiet royal approval.
The King recalled the late Queen Elizabeth’s healing of wartime wounds, saying she was “determined to play her own part” in the “immense achievement that reconciliation represented”.
These are important words in Germany, whose precious post-war friendships are guarded with the kind of anxiety that Britain feels about its “special relationship” with Washington.
Germany’s Foreign Minister Annalena Baerbock said Brexit felt like a death in the family when she recently visited London.
The King’s speech “brought to the fore our common values and the things that unite us,” Social Democratic MP Jens Zimmermann said — “a perspective that has often been in short supply in recent years”.
“I am looking positively towards the future relations between our two countries. We have a strong partner in King Charles,” he said.
The few voices that grumbled at a monarch taking the stage were drowned out by those who saluted the King and said Britain, as “one of the world’s oldest democracies”, was not to be lectured by Germany.
“I am truly no monarchist but the speech was impressive and mindful of the close relationship between our countries,” said another Social Democratic MP, Dirk-Ulrich Mende.
Day three of King Charles III's visit to Germany - in pictures
This is the soft power of the monarchy. The visit did not move Britain an inch away from Brexit or offer Germany any concrete political wins, but by pushing the right buttons the UK has won a reserve of goodwill in Berlin.
Nods to Anglo-German history were sprinkled throughout the trip.
The King met Ukrainian refugees at the former Tegel Airport, once used by British, French and American pilots to airlift food to West Berlin.
Among the talking heads on German TV was Eduard, Prince of Anhalt, an aristocrat related to King Charles via the centuries-long ties between the royal family and Germany.
Friday’s events in Hamburg, one of Germany’s most Anglophile cities with trading links to London dating back more than 750 years, were another well-judged move.
After seeing a memorial to the Kindertransport — the effort to rescue children from Nazi-controlled territory in the months before the Second World War — King Charles laid a wreath at a ruined church that was destroyed by Allied bombing in 1943.
Germany tends to hold back in mourning its own wartime suffering, accepting that it had only itself to blame, but the gesture by a British monarch was well received.
“A sign of reconciliation between two former wartime enemies, and common remembrance for the victims, is an important signal in the current climate,” said Hamburg Bishop Kirsten Fehrs.
When the late queen visited Dresden in 1992, another city ravaged by Allied air raids, she was met with jeers and eggs when she stopped short of paying tribute to the victims.
Many have doubted whether King Charles could ever match his mother’s popularity, but in Hamburg he appeared to have outdone her.