The Queen passed human rights protesters on her way to a lunch with Commonwealth heads of state today.
She attended the event alone as the Duke of Edinburgh remained in hospital with a bladder infection.
She was joined by more than 70 guests, including Prime Minister David Cameron and leaders from across the association of nations, as they arrived to angry scenes.
Hundreds of Tamil and human rights campaigners gathered outside Marlborough House in central London in opposition to Sri Lankan President Mahinda Rajapakse's presence at the meal.
Their chants echoed around the forecourt as guests arrived.
Mr Rajapakse was jeered as he swept through the main gate in a Range Rover. His car did not carry a flag because of security concerns.
The Queen seemed relaxed as she was handed a bouquet of flowers by nine-year-old Aduke Badale, the daughter of a member of the Commonwealth Secretariat staff.
The Queen wore a floral print silk dress in shades of blue and grey by Stuart Parvin and a blue wool crepe hat.
The Queen spent a brief moment with Mr Rajapakse and appeared to fleetingly shake hands with him as she met guests at a reception in the Blenheim Saloon inside Marlborough House.
Heads of state and representatives from Australia, Canada and the African nations were welcomed by Commonwealth Secretary-General Kamalesh Sharma.