LONDON, June 21 (Xinhua) -- Royal Navy warship, HMS Enterprise, has sailed up the River Thames on a rare visit to London.

The multi-survey hydrographic vessel, normally based in Plymouth, will be open to the public Saturday at London's West India Docks.

And on Monday the captain and crew will take part in an unusual ceremony dating back to the 14th century during which they will hand over a barrel of rum as a payment to the Tower of London.

A Royal Navy spokesperson explained: "This ancient custom originated in the 14th Century in the reign of King Richard II who decreed that any large navy vessel passing upstream was to pay a levy to the Tower. The levy required was a barrel of navy rum."

The ship's first official engagement Thursday night saw it hosting the newly appointed First Sea Lord, the Head of the Royal Navy, Admiral Tony Radakin, during which a sunset ceremony was performed.

HMS Enterprise's Commanding Officer Cecil Ladislaus said: "I am delighted to have had the chance to bring Enterprise to our great nation's capital. My team are excited about performing the 'Ceremony of the Dues' at the Tower of London."

Also on Monday the crew will also attend the Flag Raising ceremony at London Guildhall for National Armed Forces Day as well as the launch of London International Sea Week and London Armed Forces week.

HMS Enterprise's primary role is to conduct hydrographic and oceanographic survey which contributes to the safety of mariners both in and out of defense. Primarily a survey ship, HMS Enterprise is also a warship armed with two 20mm cannons, three Mk44 miniguns and four General Purpose Machine Guns.