In a small craft studio at a secret location in central London, some of Britain's leading sculptors are hard at work creating the masterpiece that will decorate the prow of the queen's royal barge during the Diamond Jubilee Pageant on the River Thames.

Some 3 tonnes of clay is being used to mould the baroque-style prow, which features Old Father Thames and a classical dolphin on each side.

Once the clay has been sculpted a mould will be taken, cast in fire-proof resin and then covered in 22 carat gold leaf in a rarely used 18th century technique before being fitted to the royal barge.

Britain's Queen Elizabeth is borrowing luxury Thames cruiser, the Spirit of Chartwell, as the royal barge for her Jubilee Pageant in June.

Lead sculptor, Alan Lamb said it's an honour to be crafting the prow for the Spirit of Chartwell.

They are turning this already beautiful boat into something absolutely magnificent and hopefully this is a sculpture fit for a queen, he said.

The prow will be 25 feet long on either side and 5 feet deep. It will take the craftspeople just over two months to complete.

Lamb took his inspiration from royal barges in the 17th and 18th centuries and has used traditional images associated with the long history of the Thames river.

The sculpture includes two enormous Old Father Thames, figures of Britannia riding sea horses and scaly sharp-toothed dolphins.

This big scary sea creature is a classical dolphin, so they go back to sort of Roman times, dolphins portrayed in this style, he said.

They are more like killer whales than dolphins, they've got teeth and they are quite aggressive looking, but they are very much a symbol of London and the river and some of the London livery companies use them on their coats of arms.

The Thames Diamond Jubilee Pageant in June will see a thousand boat strong flotilla sail through central London. The royal barge will lead the flotilla of pleasure, military, historic and Commonwealth boats as millions are expected to line the Thames to view the spectacle celebrating Queen Elizabeth's 60 years on the throne.

The Spirit of Chartwell is currently docked in Canary Wharf, where designers are working on covering it in regal red and gold decorations.

Inside there are 22 cabins, mahogany armchairs and tables, a steel kitchen and large bar in the style of the Orient Express.

The Jubilee prow will only be used on the Spirit of Chartwell during the Thames pageant. It will then go on display for the general public.

(Editing by Paul Casciato)