The flame will be on the road for 70 days as it is carried through villages and cities in England, Scotland, Wales and Northern Ireland, CNN reported.
"It will visit a thousand towns, and be seen by millions," Deputy Prime Minister Nick Clegg said as Ainslie prepared to hit the road. "With every step, the excitement will build. And 10 weeks from now, the world will watch as the flame arrives at the new Olympic Stadium."
Ainslie, who has won three Olympic gold medals for his skippering skills, picked up the torch on the Cornwall coast and handed it off to teenage surfing star Anastassia Swallow. More than 100 runners will carry the torch on the first day, CNN said.