The British-Indian actor, who plays astrophysics student Rajesh 'Raj' Koothrappali in the hit U.S. TV comedy, was one of a number of dignitaries from India and the U.K. invited to Buckingham Palace in London for a reception marking the launch of the UK-India Year of Culture 2017.

There, he mingled British royals including Catherine, Duchess of Cambridge, her husband Prince William, and Queen Elizabeth II herself. However Kunal, 35, initially thought his invite to meet royalty was just a friend playing a joke.

"I got an email in my personal inbox and at first I thought it was one of my friends spamming me," he told Britain's Daily Mail newspaper. "I replied and it turned out to be real. It's incredible."

Speaking of meeting Britain's monarch he said, "I did get to speak to the Queen and she said how nice it was to meet me again.

"I haven't actually met her before so maybe she was confused or has just watched The Big Bang Theory! I just shook her hand, bowed my head and said thank you so much for inviting us."

Organised by officials at the British Council and the High Commission of India in London, the year of culture celebrates the 70th anniversary of India becoming independent from the British Empire.

Other stars at the event included British-Indian actress Ayesha Dharker, Indian cricket legend Kapil Dev, sitar player Anoushka Shankar, the daughter of sitar legend Ravi Shankar, and her husband, Anna Karenina director Joe Wright.

Revealing his pride at being asked to the event, Kunal added, "The evening has just been overwhelming as I got to meet the Queen and to promote UK-Indian culture, which gives me so much pride."

"It is important to me as an Indian artist to promote Indian culture. I am an Indian character on an American TV show, so I wear my culture on my sleeve. So to be here is a part of that. "