As night falls over the capital, the Tower of London becomes a pool of darkness among the blazing glass cliffs of office blocks. Then one by one lights click on in the deep stone windows, as the residents of the medieval village in the heart of the city take back their haunted cobbled streets and courtyards.
Almost 100 people live inside the 1,000-year-old fortress, including the governor and his deputy and their families, the vicar, a doctor, the yeomen warders and some curators. They share every corner with a ghost story: grey bears and white ladies, the roar of the lions first introduced by King John in the 12th century, weeping children, screaming aristocrats on their way to the block, a disembodied silk-clad hand, an enduring smell of saddle soap from long dead horses.
"Never seen one, never heard one. I don't believe in ghosts," Phil Wilson says sternly. He has lived in the Tower as a yeoman warder since 1997, but first worked there more than 40 years ago as a young Coldstream guardsman. His scepticism is impressive, given the objects regularly found flung about his bathroom on the top floor of the 13th-century Beauchamp tower – his wife always blamed him for the towels left in a damp heap on the floor – and the gentleman in doublet and hose looking mournfully down from the battlements spotted by a house guest between the washing lines on his roof.
Normally this is a closed world to outsiders. Tourists leave at dusk, and the great main gate is still formally locked by the governor every night in the ceremony of keys. Any of the residents not home in time must either stop out until the following day or know that night's password.
From next week until April, however, small pre-booked groups will be admitted on special tours. Strictly speaking these are "twilight tours", not ghost tours, but they are part of a multimillion-pound industry in chilling the blood, which is now spreading out from Halloween into all the dark winter months.
Almost every museum in the country in an old building now runs some form of after-hours spooky event. The National Trust, whose ghosts include a priest strangled by an outraged husband at Baddesley Clinton in Warwickshire, and English Heritage, whose sites include Whitby Abbey (used by Bram Stoker as a setting for part of Dracula), list scores on their websites. The Courts of Justice museum in Nottingham and the much more modest Edward Jenner museum in Gloucestershire – which celebrates the pioneer of vaccination, a hero of rational science – have both recently posted eerie images captured by visitors in their buildings.
Ghosts in museums used to confine themselves to going bump in the night at Halloween, but have proved such a moneyspinner that, like Halloween festivities themselves, they are spreading ever wider. Dave Musgrove, the editor of BBC History magazine, says that Halloween is now threatening to overshadow the more traditional bonfire night celebrations, and defends it against the charge of being entirely an American import.
"An interesting story, revealed in our November issue, is how America's Halloween celebrations have adapted British customs that were carried to the States along with emigrants. Trick or treat, for example, appears to have derived from the Yorkshire tradition of mischief night, when young men would embark on pranks such as rapping on windows, trampling gardens and setting livestock loose."
Many museums have events that began as Halloween specials and now run throughout the dark winter months. The company that runs Mary King's Close, a genuinely eerie complex of underground streets and houses in Edinburgh, and the museum parts of Oxford castle, has included overnight training sessions led by "paranormal celebrities" for rookie ghost hunters.
At the Tower of London the tours will continue into April with a break for December. Historic Royal Palaces, the quango that runs the tourism side of those palaces that are no longer royal residences, will also launch tours from Sunday night of the equally ghost-storied acres of Hampton Court. One woman links both sites, Catherine Howard, heard and seen repeatedly as she ran shrieking along the passage at Hampton Court now known as the haunted corridor, trying to reach her husband Henry VIII to plead for her life. She never got to him, and it would have made no difference if she had: she lost her head on Tower Green and is one of the queens still said to be buried in arrow boxes under the altar in the Chapel Royal.
If Wilson doesn't believe in ghosts himself, he knows several men who do – and some of them will be leading the tours. One moved his family out of the Tower when his own very young children, who had not been told they were sleeping a stone's throw from the traditional murder spot of the little princes, said they liked living there, but not the nasty children in the funny clothes.
The twilight tourists are guaranteed to see extraordinary sights. Not, perhaps, the little princes in their night shirts, nor Anne Boleyn, executed as a special favour by a skilled French swordsman instead of the axe in 1536, nor Sir Thomas More joking on the scaffold in 1532 that his beard should be spared as it had done no harm. But the glimpses of washing-up liquid bottles perched on 12th-century window sills, or the shrieks of 21st-century children refusing to behave themselves and go to bed in rooms where saints and royalty once sat wondering if the next night would be their last, should be startling enough for anyone.
