Both our countries face a terrible threat from terrorism and we shall always work together and fight this together, Cameron added.
"But also respect for the histories, religions, traditions of our respective countries," he said refering to his visit to Amritsar last year.
"I will never forget my visit to the Golden Temple, one of the most beautiful, serene and moving places I have ever been to. Sometimes during the trials and tribulations of this job, I think of that and wish I could be there again. I am very proud to have been the first serving Prime Minister to make that visit," he said amid wide applause from a large number of British Sikhs.
We should also show respect for each other's past and our shared past, he said.
"I think it's absolutely a brilliant decision that we made this week to have in Parliament Square, alongside statues of Lloyd George and Churchill and Mandela, in time a statue of one of the greatest men of the 21st century - Mahatma Gandhi," Cameron added in reference to the recent announcement in India on a new Gandhi statue for London.
The British PM also listed "three fabulous facts" that proved the relationship between the two countries can get "even stronger."
"Firstly, Indian business is investing more into the UK than the rest of the European Union put together; second, UK is the biggest inward investor into India, so the economic partnership is getting ever greater; and fact number three is that Britain's biggest diplomatic presence anywhere in the world is actually in India," he said.
"I think that is a testament to the scale of opportunity that we see in this absolutely vibrant relationship," he aid.
The Conservative Friends of India (CFI), co-chaired by Indian-origin MP Alok Sharma and businessman Ranjit Baxi, is aimed at building stronger links between the Conservative Party, the British Indian community and India.
The annual event was attended by senior politicians, MPs as well as the Indian High Commissioner to the UK, Ranjan Mathai.
