The Queen is to continue to mark her Diamond Jubilee today following four days of public celebrations which she has described as a "humbling experience".

In a television address on Tuesday the Queen thanked the nation for organising and taking part in events to celebrate her 60 years on the throne.

The monarch is to sit down at a lunch laid on in honour of the anniversary with Commonwealth leaders, including prime ministers, governor generals and high commission representatives, The Duke of Edinburgh was due to accompany the Queen to the event at Marlborough House on Pall Mall in London but remains in hospital under observation for a bladder infection. His youngest son, The Earl of Wessex, said Philip, 90, was "feeling a lot better", adding that "a good rest is probably what is required".

The lunch follows four days of pomp and pageantry, which drew well-wishers to London from all over the world.

On Tuesday the Queen set the seal on the celebrations with a Buckingham Palace appearance before an estimated crowd of more than a million. Surrounded by the Prince of Wales, Duchess of Cornwall, Duke and Duchess of Cambridge and Prince Harry, she watched a flypast of Second World War aircraft and the Red Arrows.

In her broadcast message the Queen said: "The events that I have attended to mark my Diamond Jubilee have been a humbling experience. It has touched me deeply to see so many thousands of families, neighbours and friends celebrating together in such a happy atmosphere."

She added: "I hope that memories of all this year's happy events will brighten our lives for many years to come. I will continue to treasure and draw inspiration from the countless kindnesses shown to me in this country and throughout the Commonwealth. Thank you all."

Tributes have been paid to her throughout the weekend, including American president Barack Obama, who has developed a strong bond with the Queen, saying she was a living witness to the power of the alliance between the UK and US.

Prime Minister David Cameron, highlighting that the weekend had been a unifying event for the nation, said: "I think really it is the best of Britain. We have seen the country come together with a sense of celebration and unity but also tremendous resilience, resilience from people who want to celebrate despite the weather and resilience, of course, from Her Majesty - nothing stops her doing the job she does."