It created the biggest empire the world had ever known, one on which the sun literally never set.
And decades after it offloaded its colonial possessions, British leaders still loved to point out that their nation "punched above its weight" by exercising a far bigger global influence than a state the size of their United Kingdom would warrant.
But since the beginning of this decade, Britain's footprint on world affairs has rapidly declined, and whoever wins the British general elections a month from now on May 7 will face the same existential question which every London-based government since World War II confronted but failed to address: what could or should be Britain's world role?
It's not at all obvious that a clear answer will be provided this time either, for Britain's global "fade-out act" is not so much due to a lack of resources or a diminished economic status, but more the result of a catastrophic failure of national confidence and political vision among London's political elite.
On paper, most British officials remain committed to the idea that their country is a global player.
One of the first things the current government led by Prime Minister David Cameron did when it came to office in 2010 was to commission a Strategic Defence and Security Review which came to the bold conclusion that the nation "has always had global responsibilities and global ambitions" and vowed to "have no less ambition in the decades to come".
British officials cite endless statistics about the number of mediation initiatives and communiques the Foreign Office generated, or the quantity of United Nations Security Council resolutions Britain sponsored.
The presentation of Britain's foreign policy now resembles that of the old Soviet Union five-year plans: full of impressive-sounding but largely meaningless figures, designed to disconnect readers from the reality. And the reality is far less encouraging.
The 2010 governmental strategic review pencilled in a cut of 8 per cent in Britain's defence expenditure; that turned out to be closer to 25 per cent in real spending terms, pushing Britain down to sixth place in the rankings of global defence spenders.
For the first time in modern history, the British Parliament rejected in 2013 a government motion to authorise the use of force in Syria, a decision which not only inflicted deep damage on Britain's standing in the Middle East, but also curtailed the British government's ability to undertake future overseas military operations.
The British took an active part in the United States-led nuclear negotiations with Iran, but it was the French and not the British who showed interest in the intricacies of the deal and had the courage to stand up to the Americans when they believed that Washington gave too much to the Iranians.
It is France which now enjoys close military ties - as well as lucrative weapon sales - with Saudi Arabia and other Gulf states, countries which once looked to London for guidance and support.
Britain is also nowhere to be seen in the handling of the current crisis in Ukraine, the worst challenge to European security since the end of the Cold War a quarter of a century ago.
London was quite content to leave such matters to the Germans and the French, and to be briefed by them on the outcome of the diplomatic negotiations with Russia.
The British also seem curiously relaxed about the future of their relationship with the US, once the key pillar of their security arrangements; Mr Cameron seldom confers with President Barack Obama, and almost never refers to the transatlantic "special relationship".
And when it comes to China, the British are now guilty of what they criticised others for doing: treating China as a big economic lump where money can be made, rather than as a broader strategic challenge; Britain's policy towards China is now largely dictated by the UK Treasury.
Even when the British still claim centre-stage, that's often just a game of smoke and mirrors, of "virtual reality", to use a more polite and recent term.
Britain claims to be leading by example in the fight against the so-called Islamic State in Iraq and Syria terrorists in the Middle East. But in hardware terms, this consists of precisely eight jets which, on average, undertake one bombing mission a day.
And when the Defence Committee of the British Parliament recently visited Iraq, it found out that the British have only a handful of soldiers for liaison purposes on the ground, compared to hundreds supplied by countries such as Australia.
Other examples of claims confounded by realities abound.
The British High Commissioner to Singapore recently chided the author of this article for claiming that London no longer takes seriously its obligations under the so-called Five Power Defence Arrangements which were designed to support Singapore's security.
And, indeed, a reference to these military arrangements features prominently on the front page of the British High Commission's website.
Unfortunately, when one clicks on this reference, all one gets as "proof" of recent British security activity in South-east Asia is a reference to a conference on the subject organised by Australia's air force at the beginning of this decade; such is the difference between official claims and humdrum realities.
Finally, the British assert that they continue to have a "world-class" diplomatic service.
Yet the entire budget of London's Foreign Office is now less than what the British spend each year on subsidising winter-time heating fuel for their elderly, one of the smallest parts of Britain's welfare system.
That's not necessarily dishonourable, but it serves as a good indication that despite claims to the contrary, London's top priority may not be the defence and foreign policy of the nation.
A variety of explanations exists for this decline.
A national backlash against a decade of frequent military interventions ordered by former premier Tony Blair in the Balkans, Africa and Iraq has certainly reduced appetite for foreign adventures.
The financial crisis which struck Britain also took its toll.
And then, there is the personality of Mr Cameron, who simply doesn't care about foreign policy matters and spends little time reading the briefings provided by his civil servants.
The results are very often botched foreign policy debates, followed by even more botched foreign policy initiatives.
In theory, all these factors are transient: a new prime minister who may be elected in a month from now could rediscover Britain's global vocation. Sadly, however, the chances of that happening are fairly slim.
For Britain is now affected by a curious feeling of impotence, coupled with an obsession with domestic issues.
London-based politicians are much more interested in countering a threat from the Scottish National Party to break up the United Kingdom, coupled with demands from the chauvinist UK Independence Party for a complete British withdrawal from the European Union.
But even if a future British government succeeds in deflecting these pressures, Britain is unlikely to make a serious intellectual or political contribution to strengthening European security arrangements. It may remain in Europe, but not be part of Europe.
Does all this matter? Yes, a great deal. For Britain is still one of Europe's powerhouses; London has the highest concentration of security think-tanks on the continent, and they provide a constant flow of excellent analysis.
British politicians can also rely on a well-oiled intelligence machinery which strengthens their understanding of world problems.
Britain is also a good global citizen: its overseas development aid programme has increased by an astonishing 27 per cent over the past few years, with most of it directed to reducing poverty in the world's most needy nations.
And although it's unlikely that Britain will honour its pledge to continue devoting at least 2 per cent of its gross domestic product to its military, the current UK government is still committed to spending £159 billion (S$320 billion) in new weapon purchases over the next six years and remains one of the few in Europe with truly global deployment capabilities.
"Write Britain off at your peril," wrote Professor Brendan Simms of Cambridge University, an authority on international relations. Perhaps he's right.
Still, it may take a while before the country regains confidence in itself, and elects a prime minister who defines his or her mission as something a bit more than just clinging to power by avoiding all the hard choices.
