After visiting a Tata Motors-owned Jaguar Land Rover factory in the West Midlands region of England, Modi boarded a flight from Heathrow Airport to Antalya in Turkey to take part in the G20 summit, which opens tomorrow.
"My gratitude to the British people & Govt. Special thanks to PM @David_Cameron for his personal attention to all the aspects of my visit," Modi tweeted before his departure from the UK.
"The progress on the economic front was satisfying. India & UK are partners in development & our economic cooperation is all set to increase," he said.
Modi's three-day tour had a packed schedule that included delegation-level talks with his British counterpart Cameron, lunch with Queen Elizabeth II at Buckingham Palace, a speech to British MPs and an address to the Indian diaspora at the Wembley Stadium.
In Turkey, Modi will attend the G20 Summit, chaired by Turkish President Recep Tayyip Erdogan. The summit will focus on the current state of the global economy, sustainable growth, development and climate change, investment, trade and energy.