"As millions of people mark this important milestone we can reflect on the enduring and special relationship between our two nations – the world's oldest democracy and its largest," Cameron said in a statement from Downing Street.
"This relationship has gone through great changes. Our collaboration is now stronger, deeper and more far-reaching.

It is a partnership between two equals with a mutual respect for each other," he added.
Cameron's deputy from the Liberal Democrat party, Nick Clegg in his message, said: "The 65th India Republic Day is a very significant milestone in your history and an opportunity to celebrate your incredible achievements.
"On my recent visit to India I was reminded of the continuing strength and unique warmth of the very special relationship between our two countries."
He went on to highlight how Britain would not be the same without the extraordinary contribution of the Indian diaspora in business, cultural and sporting life.
"So let us celebrate this important day together, as two like-minded democratic nations whose bond of friendship grows stronger every year," he added.
British Premier's UK-India Diaspora Champion and UK Treasury minister Priti Patel also hailed the historic
relations between the two countries in her message.
"The Republic Day celebrations remind us all of the strong and deep ties between our people and our governments and the importance of the partnership between the UK and
India: the oldest and largest democracies in the world," she said in a statement.
Britain's senior-most Gujarati-origin minister also referred to the planned statue of Mahatma Gandhi in Parliament Square in London, to be launched this year, as a symbol of the close India-UK ties.
"The much-anticipated statue of Gandhi in London's Parliament Square in London will also carry huge resonance in both our nations and across the world.


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