* Cameron warns Argentina after Falklands referendum
* Islanders vote overwhelmingly to remain British territory
* Britain defeated Argentina in 1982 Falklands war
By Shadia Nasralla and Maria Golovnina
LONDON, March 12 (Reuters) - Prime Minister David Cameron warned Argentina on Tuesday that Britain would always be ready to defend citizens in the remote Falkland Islands after they voted almost unanimously in a referendum to remain British.
Argentina, 300 miles (500 km) to the west of the Falklands, has claimed the South Atlantic archipelago for almost 200 years and in 1982 invaded the islands only to be repulsed in a 74-day war with Britain.
British nationals first settled in the Falklands in the 19th century and now, three decades after the war for ownership of the islands, many still feel strongly about their fate.
"The Falkland Islands may be thousands of miles away but they are British through and through, and that is how they want to stay, and people should know we will always be there to defend them," Cameron said in televised remarks.
"They want to remain British and that view should be respected by everybody, including by Argentina."
In a referendum on Sunday and Monday designed to send a defiant message to Argentina, all but three of those who cast their ballots on the islands voted for them to remain a British Overseas Territory.
In their ancestral homeland 8,000 miles (12,900 km) away, British television channels ran continuous live coverage from the chilly, windswept and sparsely populated islands over the weekend, and Britons praised the islanders for voting "yes".
"It's a British colony. The settlers out there are all British," Tony Gill, 74, a former military pilot, said in the town of Chelmsford in eastern England.
"They've made the island what it is and now the Argentineans want to take it away from them," added Gill as he headed to a meeting with other veterans including some of those who fought in the 1982 war.
Speaking alongside Gill at a local bus stop, Brian Polson, another veteran, nodded and added: "You defend your own."
Argentina's left-leaning president, Cristina Fernandez, has piled pressure on Britain to negotiate the sovereignty of the islands - something London refuses to do unless the islanders themselves request talks.
About 650 Argentines and 255 Britons were killed in the 1982 war that started after Argentinean forces invaded the islands, prompting Britain's prime minister at the time, Margaret Thatcher, to dispatch a naval task force to retake them.
Most Argentines think the islands - known as the Malvinas in Spanish - rightfully belong to the South American country and they remain a potent national symbol that unites political foes.
Before that war, few in Britain even knew where the islands were located. Former Defence Secretary John Nott once recounted that he had to consult a globe in his office to remind himself of the geographical position of the Falklands. "I was a bit horrified to see how far away they were," he once said.
But now Britons seem much more emotional on the issue. In Chelmsford, a city in the London commuter belt praised as the birthplace of radio, many people interviewed by Reuters felt Britain should stand by the British on the Falklands.
"They reckon they're British, therefore it's up to us to look after them," said Joyce Maurer, 66, a receptionist at a Baptist church in Chelmsford, about 55 km (35 miles) northeast of London.
"You can't just desert the people and leave them to their own devices because if they've chosen to be British then they have to be looked after. And if it came to it, we'd have to take military action."
But some, particularly younger people, appeared less enthusiastic about the fate of the islands' 1,649 inhabitants.
"I don't really care. But I do think they should remain British because its part of our heritage. But if it doesn't, it doesn't," Liam Clancy, a 20-year-old student, said with a shrug.
"If the people that live there class themselves as being British then Britain should defend it. ... It's not going to affect my life. I don't think my friends even know about it." (Writing by Maria Golovnina; Editing by Mark Heinrich)