The cast of Quantum of Solace pose for a photocall

By Tim Masters Entertainment reporter, BBC News

Warning this story contains plot spoilers.

The secret is out. Although it doesn't trip off the tongue too easily, the 22nd James Bond film is now officially called Quantum of Solace.

While it may sound like a progressive rock band from the 1980s, the title actually comes from a short story by Ian Fleming in which 007 attends a dull dinner party in The Bahamas.

The announcement, three weeks into the main film shoot at Pinewood Studios, will only serve to heat up the already frenzied speculation about the new James Bond film.

As film fans began to dissect the deeper meaning of Quantum of Solace, journalists were given the chance to tour the sets on the vast 007 sound stage in Buckinghamshire.

And there were plenty of clues about what we can expect from one of the most eagerly anticipated films of 2008.

Olga Kurylenko and Gemma Arterton star alongside Daniel Craig

The budget for Quantum of Solace is larger than that of previous film Casino Royale (the producers won't say exactly how much), but it's not hard to see where the money is being spent.

Re-creating Italy

Among the sets at Pinewood is a cavernous interior of the art gallery in the Italian City of Siena. It is here that Bond has an explosive fight scene, as revealed in some early footage released by the studio.

Several statues - some eight metres tall - stand around the gallery set, wrapped in clear plastic - presumably to protect them from the pyrotechnics.

Producer Michael G Wilson has let slip that the new film will open with a big car chase in the streets of Siena. He's also mentioned an ambitious free-fall sequence involving motion-control cameras.

Another Siena-based set is a subterranean MI6 safe-house with a deep-water well. It's more like a crypt out of a Harry Potter film, with massive stone columns and huge wooden beams.

Even gloomier is a complex of tunnels - the Siena cisterns - which are so realistic that you feel genuinely deep underground when walking through them.

The action of the film isn't confined to sets at Pinewood. Location filming will also include Austria, Italy, Panama and Chile.

Inside M's office

Dame Judi Dench reprises her role as Bond's boss, M

But the most impressive set at Pinewood has to be the MI6 headquarters. A massive two-storey interior with ultra-modern décor, marble floors and frosted glass doors.

We are taken to see Dame Judi Dench as Bond's boss M filming a scene in her office. The crew is shooting close-ups of M as she speaks to her assistant Tanner (played by Rory Kinnear) in an adjoining office.

Here's a detail for Bond gadget obsessives: when M wants privacy she can touch a button and the glass wall that separates their offices frosts over. Not as impressive as an invisible car - nor as ridiculous.

Leaving the MI6 set, the illusion is quickly broken - the outer shell is all plywood and gaffer tape.

It's also hard to miss the member of the film crew who has just heard some news on his walkie-talkie.

"Quantum of Solace?" he says, with a slight look of disbelief.

Now that was a well-kept secret.