Chief Yeoman Warder, John Keohane

We are the eyes and ears of the Tower of London. And as Chief Yeoman Warder, I'm in charge of all security. My historical title is Gentleman Porter and my badge of office, the crossed red keys, indicates a porter's duties. Each night at 10pm, as for 700 years, the gates are locked in the Ceremony of the Keys.

The 35 Yeoman Warders - including ‘our Moira' who was the first woman to be appointed back in 2007 - have been guardians of the Tower (which actually has 20 towers) for five centuries. Now famous as home of the Crown Jewels, it was a royal residence and then a prison for high-ranking members of the aristocracy - and queens.

The last prisoners were the Kray twins, East End gangsters, who'd been called up to the army unit here for National Service, but deserted - they were at their mother's house having a cup of tea. They went into the military cells on either side of the clock. Rudolf Hess was held here briefly during the War. Josef Jakobs, a German spy, was the last to be executed - down by my house, actually, in what's now a car port: it used to be a firing range.

In the early days, Yeomen Warders were paid not in money but food, especially beef, which was a luxury - hence the nickname of Beefeater. The traditional scarlet-and-gold uniform, with tights and ruff, is worn only on ceremonial occasions. It's very heavy, and, in 1858, we were given permission for our blue ‘undress' uniform by Queen Victoria. We now work for Historic Royal Palaces, a charitable trust, while retaining the our military traditions.

I came in 1991, after 27 years in the Army - one selection criterion is to have served 22 years in the forces. I was considering a second career in HM Customs and Excise: its headquarters are near the Tower, and I got talking to some Yeomen Warders - and realised I was eligible to apply.

What surprised me most was that this is a village. Inside the Tower live 47 families, some with young children - Warders, Governor, curator of the Crown Jewels, chaplain and doctor. Some live in houses round Tower Green, but my home is one of those in the outer wall, in a converted stable with arrow slits for windows at the back.

People don't realise this is a community, asking, "are you married?" as if we've taken a vow of celibacy. Other odd questions include, "Which side of the river is Tower Bridge built on?", "Why didn't the White Tower have an elevator installed?", "Are there vegetarian Beefeaters?" "How often do ravens die?" Well, once, usually... we have nine ravens, cared for by the Ravenmaster. He lets them out in the morning, and buys their meat from butchers at Smithfield Market.

I'm what one expects of a Yeoman Warder - big and bearded. But once a year I shave off my beard to be the Fat Controller at the Thomas the Tank Engine weekend on the South Devon Railway. I have a house nearby, at Buckfastleigh. When I retire, I will spend my time on the railway - my third career.

Tower of London, Tower Hill, London EC3N 4AB; tel: 0844 482 7777 or visit www.hrp.org.uk/TowerOfLondon. Due to its popularity, the Ceremony of the Keys is ticketed and needs to be applied for in writing. See the website for further details on the application process.