Anniversary of 'personal union' that gave Britain its first prime minister and constitutional monarchy marked in UK and Germany

Three hundred years ago on Friday, parliament called on an unremarkable, if not downright dull, German princeling and invited him to wear the British crown.

It had been a long quest. But the shy and ailing Stuart queen, Anne, would die leaving no surviving children despite enduring 17 pregnancies, and the list of her close relatives was inconveniently long on Roman Catholics – who were banned from the throne under the 1701 Act of Settlement.

Georg Ludwig, Elector of Hanover, may have been 52nd in line, may have spoken little English, but he was at least a Protestant, and a great-grandson of James I to boot.

At a time of poignant commemorations of a far less auspicious chapter in Anglo-German relations – the centenary of the first world war – it is hardly surprising that the 300th anniversary of George I's succession on 1 August will not win front-page headlines.

But "the personal union" between Britain and Germany bequeathed not just the largely dysfunctional family soap opera that was the Georgian kings – handily reduced by CBBC's Horrible Histories to the sad, bad, mad and fat (satirised as a boy band, right). It sealed, too, a shift in power from throne to parliament, led to Britain's first prime minister in the Whig Robert Walpole, and firmly cemented the wobbly foundations of our present constitutional monarchy.

Whether any of this was the intention of George I – or the "Turnip King" to his surly new subjects, who believed Hanover a rural backwater – is unclear.

Rather, believes Christian Schnee, a lecturer in communications whose new biography, Georg I: Ein Welfensohn zwischen London und Hannover, is the first of the king to be published in German, it was probably all down to his complete ineptitude at public relations, his failure to marshal popular support, and his volatile temper.

Having been proclaimed king, George arrived on British shores in September 1714, aged 54, leaving behind a wife locked up for adultery, and with a woman on each arm rumoured to be his concubines – a large one nicknamed the "Elephant" and a skinnier one, the "Maypole". In fact the former was his illegitimate half-sister. That didn't stop salacious gossip, with one courtier, Lord Chesterfield, putting it about that the new king "rejects no woman, so long as she is very willing, very fat, and has great breasts".

"He never fully succeeded in asserting his power," said Schnee. His attempts would have been marred by xenophobic courtiers and the fact that he hardly ever attended cabinet meetings.

Though fluent in German, French, Dutch, Italian and Latin, he struggled to follow conversational English.

Initially his son, the future George II, translated for him in cabinet. But the king sent him packing from Hampton Court after a ludicrous row when a courtier, misunderstanding the younger George's thick accent, thought he had been challenged to a duel.

Then, said Schnee, the king just stopped going, telling his chief minister: "'Look, you tell me once a week what is going on.' And this is the tradition still going on to the present day, where once a week the prime minister reports to the Queen."

With the king's heart in Hanover, where he regularly returned for lengthy summer visits, his limited interest in British affairs, and the rival court set up by his own son George and his charismatic wife Caroline, George I relied increasingly on the politically astute Walpole, who was able to step up and in effect become Britain's first ever prime minister. The convoluted machinations of court and parliament at the time were savagely satirised in the Lilliputian rope-dancing contortions of Jonathan Swift's Gulliver's Travels.

Sebastian Edwards, curator at Historic Royal Palaces (HRP), whose Glorious Georges season marks the anniversary with exhibitions and events at Hampton Court, Kensington and Kew Palaces, believes George I is "underrated" as a monarch. Historians are rethinking him and concluding "he did a pretty good job at a bad time for the country," said Edwards. "He did his job, his duty, which is the thing that Hanoverians were very good at." Though from an "absolutist" background, he "stuck to the rule book", didn't splurge his civil list, and tried to improve his public image by dining in public and introducing "drawing room" meet-and-greets.

More importantly, George arrived "fully-formed" with children and grandchildren aplenty to keep the line going. Their influence on the arts, design and science is celebrated in the HRP exhibitions, including a re-creation at Hampton Court on 14 September of the Georgian pyrotechnics which accompanied Handel's Music for the Royal Fireworks. At the Queen's Gallery at Buckingham Palace, the anniversary is celebrated with the exhibition The First Georgians, Art and Monarchy 1714-1760.

The tricentenary is also being marked by concerts and opera in Germany, including an exhibition in Lower Saxony featuring George's glittering state coach and satirical pamphlets of the day. The German tourist board has introduced a royal heritage route to entice tourists to come to the country and visit places with royal links, launched at the Tower of London by Prince Ernst August of Hanover, who is married to Caroline of Monaco and is a descendant of Georg Ludwig.

Edwards believes that beneath George's "dullness" he hid "great capability". "He is caring for two countries at once, fairly effectively.

"And during this time, the country does very well. We don't get invaded, trade flourishes, the arts flourish, not directly because of the king's involvement but because he lets it happen, he trusts the politicians. He talks to Walpole," he said.

As to the Georgian dynasty, "it's soap opera stuff, very dysfunctional," said Edwards. "Unfortunately, nobody knows really that much about them because they have been written out of the curriculum."

• This article was amended on 1 August 2014 because an earlier version said George I was a grandson of James I to boot. This has been corrected to say great-grandson.