Titbits from the Ritz in the Blitz

What words would you associate with London's grandest hotels? Perhaps luxury; wealth; discretion; deference; hush; privacy and exclusivity.

Or how about spies, abortionists, suicides, conmen, communists, royals and rats? During the Second World War, the Ritz, Claridge's, the Dorchester and their ilk took on new roles as air-raid shelters for the rich, bolt-holes for crowned heads and venues for espionage, intrigue and crime.

I meet Matthew Sweet, author of The West End Front: The Wartime Secrets of London's Grand Hotels, outside the Savoy, where he seems unimpressed by its snazzy Art Deco renovation. We slip round the side to a service road roaring with generators and fans, to see the site of the famous Savoy strike of 1947. In a protest against bad treatment of staff, activists besieged the hotel, chanting the age-old slogan "Fuck the police!". Sweet shows me where the strikers lay down in the road in an attempt to block fuel tank-ers. Without oil to keep the radiators going and the sewage pipes pumping, the Savoy "would soon lose its identity as a cosy Thameside fairyland and become a dark, chilly place full of the smell of food waste and unflushed toilets", as he vividly puts it in the book.

After examining the decidedly unglamorous side of the hotel, with black-clad staff members watching us curiously over their cigarettes, we climb the steps back up to the Strand and wander to the Waldorf. As he tucks into the eponymous salad, I ask him about the genesis of his book.

It grew out of a Channel 4 series that he presented about great hotels, and also from a 1997 trip to Albania for The Independent on Sunday. "I heard from King Leka the story of how his father, six aunties and all their bodyguards and flunkies took an entire floor at the Ritz during the war," he explains. "The papers were full of stories about how the Zogs were paying their bills in bullion that they'd brought in in their hatboxes. I don't know whether they shaved a little bit off or they just waited for the bill to get so big that they could hand over a whole bar ...."

The tale set him thinking. "These buildings clearly had a role to play in wartime that was different from their peacetime role. They were the receivers of all these crowned heads from all over Europe. And also they were places where eccentric and fascinating and privileged indigenous people lived too, so that aristocrats whose staff had inconveniently gone off to fight the war had somewhere to live. They were perceived, not terribly accurately, as being very safe."

The result is a dazzling social history, full of cherishable eccentrics such as Queen Marie of Romania, the dragon of Claridges: "She went round in a uniform of her own devising, with a Sam Browne holster. Everyone was terrified of her. She didn't get out of bed until teatime." Then there's Marie-Jacqueline Hope-Nicolson, who hung out at the Gargoyle club with Lucian Freud, Guy Burgess and Dylan Thomas, who once licked gravy browning off her legs. "She was from a very eccentric family. Her father was a believer in the divinity of King Charles I. She talked about all this as though it was perfectly normal."

Less cheerfully, hotels have always been associated with suicide and murder. "Where else can you go for a comfortable room where nobody knows you and the doors all lock?" Sweet says with grim relish. "Where privacy is seen as one of the things you buy. Why not commit suicide in a luxury hotel? It's not like you'll have to pay the bill," he chortles.

One of Sweet's most devastating chapters concerns Mary Pickwoad, a bonny brunette who died at the hands of an abortionist in room 365 of the Mount Royal Hotel in 1942. No doubt scores of other women died in a similarly awful fashion, but her story was navigable in the National Archives due to her uncommon name. "Because there were so many cases like this, I wanted the story of one set of people to whom this had happened, but I had to start with one where everybody wasn't called Smith."

One particular character, however, had a very fat dossier: the suspected Nazi agent Stella Lonsdale, who holed up in room 519 of the Waldorf while being interrogated by MI5. The hotel has agreed to let us take photographs in her former room. Sadly it has been so extensively remodelled that there is not a hint of its most scandalous occupant. "I became a bit obsessed with her. She has this tremendously persuasive quality," Sweet confesses. "I was so delighted by the idea that these tough guys from MI5 were totally discombobulated because she had this very brilliant strategy of talking dirty to them. And they just couldn't deal with it!" He roars with laughter.

After the war, Stella became embroiled in dodgy dealings with various museum pieces which unexpectedly came on the market. "It's said that Bruce Chatwin had some role in that, and that it may explain why he went to Patagonia – he wanted to get away from this brewing scandal." Not just a colourful rogue, Stella probably betrayed a young man executed in occupied France. "And there's a strong chance that she killed her last husband by injecting him with floor polish. Certainly getting too close to her could be hazardous."

Looking at the photograph reproduced in the book, Stella is not a classic beauty, though her gaze has a steely quality. She's one of the people Sweet didn't get to interview – possibly fortunately. "I didn't miss her by too many years; she only died in the 1990s. But as one of her friends said to me, 'If you were asking her the questions that you're asking now, you'd probably be dead .... She'd poison that coffee.' He was joking ... but not really!" Sweet gives another roar of laughter. Stella, and Room 519, keep their secrets still.

The West End Front, By Matthew Sweet (Faber and Faber £20)

'What happened beneath the Savoy Hotel on 14 September 1940...depended on the position of the observer: whether she or he was Red or anti-Red; East Ender or West Ender; dreaming of revolution or restoration. When those 40 or 80 or 100 arrived at the doors of the hotel, a small army of journalists was on the premises for a briefing by the Ministry of Information. Few, however, wrote about their uninvited fellow guests until the war was safely over.'