For all its thick stone walls, armed guards and huge towers, the Tower’s security would not be complete without a humble lock and key. Each night, the main gates of the Tower of London are secured by the Chief Yeoman Warder and his armed guard, who then ensure that the monarch’s keys are returned to safe storage for the night. Astonishingly, this ceremony has been repeated every night without fail for more than 700 years, and you can watch this unique piece of history by applying for a free ticket.

At 9.30pm every evening, those with tickets are escorted from the main entrance to Water Lane, where a jovial Yeoman Warder talks them through the proceedings. The warders are very good at setting the scene and building up your anticipation, and it’s easy to feel a shiver up your spine as you wait in the flickering lantern light for the procession to start. Just before 10pm the Chief Yeoman Warder, his distinctive red coat and Tudor bonnet standing out against the ancient stone, emerges from the Byward Tower carrying The Queen’s Keys and a lantern. Visitors will see him walk onto Water Lane and be joined at Traitor’s Gate by his armed guard, who all salute the keys as they then proceed to the outer gates as a group.

The Chief Yeoman Warder proceeds to lock the series of large gates, outermost first. You will then see him emerge from the darkness and walk back along Water Lane towards Traitor’s Gate, where he is stopped by a sentry and asked to prove his identity. After confirming that he carries “The Queen’s Keys”, he walks through the Bloody Tower archway to where the main body of the guard is assembled. Visitors swiftly follow behind him to catch the last of the ceremony, in which the Chief Yeoman Warder asks the guardsmen to present arms, then raises his bonnet and calls “God Save Queen Elizabeth” to which everyone – audience included – replies “amen”. The Last Post is played and then the ceremony ends as the guard is dismissed and the keys stored safely for the night. All that’s left for visitors to do is escape before they are trapped overnight!

As a visitor, it’s impossible not to be struck by the incredible precision and dignity with which the ceremony is carried out, and to feel rather insignificant in the face of a living tradition that is so old. Being part of the ceremony is both a memorable privilege and a fantastic way of experiencing the rich history of London and the Royal Family. Anyone wishing to apply for tickets will need to do so at least two months in advance (three during the summer) and be flexible in your choice of dates. For full details of the formal application process, visit the Tower of London website.

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As a member, you and your family can visit London’s five Historic Royal Palaces for free, all year round, including The Tower of London, Hampton Court Palace and Kensington Palace.

As well as discounts in HRP catering outlets, you’ll also have the chance to meet the curators, gardeners and celebrity members behind London’s Historic Royal Palaces.

Prize winners will  also be invited to the exclusive members-only Ceremony of the Keys in January 2012.

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After working opposite the Tower of London for several years, I finally made the trip across the river to one of London’s most iconic venues for an evening tour.

Before visiting, I hadn’t realised just how important the Tower was to London. It once housed the Royal Mint (where Isaac Newton was warden), the Royal Observatory (which later moved to Greenwich) and the Royal Menagerie (later to become London Zoo).

With 1,000 years of history within the Tower walls, it would be easy to spend a whole day exploring. We only had an hour but that was still enough time to see a few points of interest including the spot where Anne Boleyn was beheaded (and her grave), the beautiful White Tower and the Chapel Royal of St Peter ad Vincula.

One of the most exciting aspects of the tour was getting to meet a Yeoman of the Guard (better known as a beefeater) who showed us around. Beefeaters have always played an important role at the Tower – once upon a time they transported the severed heads of executed prisoners from Tower Hill to London Bridge; here the heads were displayed as a warning of the fate awaiting any would-be traitors!

Happily, beefeaters have a less grisly job today, with tasks including taking care of the Tower’s resident ravens, leading tours and locking up the Tower at night. There are also a few perks involved in being a Yeoman of the Guard. Once upon a time, they were paid in rations including meat (one of the origins of the name beefeater) and now, the Yeomen of the Guard and their families are allowed to live on site, at the Tower of London.

As it was an evening tour, we were lucky enough to witness the locking of the Tower, known as the Ceremony of the Keys. During the ceremony, the Chief Yeoman Warder secures the Tower accompanied by a military guard, ending with the Last Post.

The ceremony takes place at 9.53pm exactly, finishing at 10pm. There’s only one time in history when there was a delay in closing the Tower – during an air raid in the Second World War, when it ran six minutes late.

Despite gate after gate being securely locked, we weren’t stuck inside for the night. After the ceremony, small doors in the gates were opened for visitors to exit. We wondered if there’s a ceremony for the locking of these doors once everyone had left?

Jenny was a guest of Global Hotel Alliance (GHA) bringing together 12 independent hotel brands. The Tower of London private evening tour is available as part of the GHA Discovery Programme, a loyalty programme offering amazing local experiences to members.

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Find out more about applying to watch the Ceremony of the Keys