The Middletons - Kate's parents Michael and Carole and siblings Pippa and James - were invited on board the paddle steamer the Elizabethan for the epic tribute to the Queen.

While Kate and her husband the Duke of Cambridge join the monarch, the Duke of Edinburgh, the Prince of Wales, the Duchess of Cornwall and Prince Harry on the Royal Barge, the Spirit of Chartwell, the Middletons will be close by on another of the Royal Squadron vessels.

The Elizabethan is described as having ''the unique exterior of a 19th century Paddle Steamer coupled with the interior of a top London restaurant and night club''.

The Middletons are expected to be joined by Charles's former valet Michael Fawcett.

The Duke of York, Princess Beatrice, Princess Eugenie, the Earl and Countess of Wessex, the Duke and Duchess of Gloucester and Prince and Princess Michael of Kent will sail on the Havengore joined by the Mayor of London Boris Johnson and former Prime Minister Sir John Major and his wife Dame Norma Major.

The Havengore was used to transport Sir Winston Churchill's body along the Thames on the day of his state funeral in 1965.

The Princess Royal and Vice-Admiral Sir Timothy Laurence will travel on Trinity House No.1 Boat, while the Duke of Kent and Princess Alexandra be on board the RNLI Diamond Jubilee.

The Duchess of Kent, who does not normally attend royal events, will be on the Henley steam launch - one of the oldest passenger boats in daily service on the Lower Thames.

With the Queen, on the Spirit of Chartwell, are expected to be the Bishop of London, the Poet Laureate Carol Ann Duffy, former owner of National Car Parks Sir Donald Gosling, the Queen's lady-in-waiting Lady Susan Hussey, the monarch's equerry Lieutenant Colonel Dan Rex, her waterman Christopher Livett, Kamalesh Sharma, the Secretary-General of the Commonwealth and historian Simon Schama.

Prime Minister David Cameron and wife Samantha will wait on HMS President close to Blackfriars Bridge for the Queen to join them.

Politicians including Labour leader Ed Miliband, Deputy Prime Minister Nick Clegg and Chancellor George Osborne will watch from the Design Museum on the riverbank.

The royal barge Gloriana, which will lead the pageant, will be powered by 18 oarsmen including Olympians Sir Steve Redgrave and Sir Matthew Pinsent, Paralympic athlete Pamela Relph and Corporal Neil Heritage, who lost his legs while serving in Iraq.

Foreign Secretary William Hague will be on the Sarpedon passenger boat, while the Sapele will ferry George and Victoria Cross heroes including Lance Corporal Johnson Beharry.