Politics upstairs and spies in the basement; if you’re spending a few days in London this summer check out the Royal Horseguards hotel and its venue next door One Whitehall. It was built as a club and rooms for the Liberals in 1884 (not being as posh as the Tories, they didn’t have London townhouses to stay in when they left their country estates) in the style of a French chateau; look up from the Thames to its fabulous river frontage and you could be forgiven for thinking you’re on the Loire.

The National Liberals Club still use one floor of the building for its members and meetings, further up the impressive freestanding marble staircase (thought to be the largest in Europe) is the Gladstone Library, now used for weddings and events.

Another formidable room with a lofty ceiling, faience-tiled columns and impressive fireplaces at each end was surely the scene of some great ceremonious occasions? But no, it was the billiard room, where Gladstone and the boys shot balls and the breeze. Down at one end is a curtained balcony. ‘What’s that?’ I ask the blue badge tour guide who is showing me around. ‘That’s where the ladies could watch from,’ he replies – they weren't allowed into most of the rooms in the building. Thoughtfully though, so they didn’t have to spend their entire time crammed in the balcony, wishing desperately for a cup of tea, there was a ‘Ladies room’ provided nearby – smaller than the other rooms, naturally, they didn’t have as many egos to squeeze in …

Down in the basement there are flights of steps leading to blocked-off secret tunnels. The building was used as MI5’s headquarters during the First World War when a man called ‘C’ who had a wooden leg and wrote in green ink ran the show. The Ministry of Defence pretty much moved in during World War II and Churchill stopped in regularly for a nightcap. In centuries preceding this was a royal area, the Palaces of Whitehall standing on this site until the Great Fire of London and neighbouring Scotland Yard getting its name when the Scottish kings took up residence. Only the nearby Banqueting Hall of Whitehall remains of this royal legacy.

It’s a fantastic bit of London history in an area where most buildings are closed off to the public – just try wandering around the corner to Downing St and asking to see their basements. Stay overnight if you’re feeling flush (from £225 per room per night, subject to availability), or treat yourself to afternoon tea (from £16.50 per person).

Royal Horseguards Hotel, 2 Whitehall Court, London SW1A 2EJ, phone 0871 376 9033 or visit the website here.