BEHIND THE SCENES with Neville Edwards and Cathy FitzGerald

Have you had many experiences in museums after dark? What were they like? Did those experiences inspire this story? Cathy FitzGerald: If only! No, the idea grew from a conversation with a friend about what that experience might be like and where we'd hide out if we could. There's a room full of clocks and astrolabes at the British Museum, which was always my favourite –- very cosy with a reassuring tick. And then I saw a short film by the Brothers Quay called The Phantom Museum , which is very strange and very beautiful –- a dream-like journey through the Henry Wellcome Collection in which the objects come to half-life and a floating pair of white cotton gloves opens cabinets and drawers. It composted away in my imagination for years, until I started work on the National Gallery Podcast and realised I had a chance to make something out of that fascination. That was when I finally got to wander around a museum after dark. We recorded all the interviews in the Gallery late at night. It's a maze of half-lit, high-ceilinged rooms, quite cold, and all you can hear is the low drone of the air-conditioner and the faint sound of traffic in Trafalgar Square. If you're there alone it doesn't take much to conjure a sense of inhabited emptiness. As Ben Stiller has shown us all

Why did you decide to bring the paintings to life in the piece? Did you have particular paintings (or other works of art) in mind when you imagined those voices

CF: I wanted to create a piece that would make listeners feel as well as think, so that they'd take away ideas, but also –- if they shut their eyes hard –- some impression of the sensory and emotional experience of being in the Gallery after dark. So we had to find a way of representing the uncanny sense of presence that the paintings have, even during the daytime. Poetry seemed a good way of doing that because there's something inherently spectral and strange about it as a form. Our contact at the Gallery, Elena Lagoudi, knew a spoken word group called Malika's Kitchen, and that's how we got in touch with Aoife Mannix and Jacob Sam-La Rose, who wrote and performed original work in the episode. We asked them to bring the paintings to life -– but to avoid anything too literal or definite. I don't think the piece would have worked if Holbein's Ambassadors had craned out of their frame to have a chat with the warder, for example. Can you talk about the sound design that's used to conjure the "after hours" feel of the Gallery? Neville Edwards : I recorded lots of atmosphere and actuality while at the Gallery at night and used that blended with patches from mostly soft synths to create an ambience that suited the otherworldly feeling Cathy wanted to convey. Rather than a cinematic approach I tried to suit the mood, often using the faintest of drones or the slightest jangle of the guards' keys to fill out the space around the narrative of the documentary. The Gallery at night itself had its own unique sounds, air conditioning, walkie-talkie squawk, flickering lights, the reverberations of doors in such empty big spaces, and I tried to blend these into a more synthetic and dreamlike soundscape by either sample manipulation or by the copious use of effects and treatments. The poetry sections we also choose to be effected, this time with simple EQ'd delay, to both separate them from the rest of the documentary and to add to that sense of detachment and ghostliness, as if the paintings' thoughts were echoing around the empty rooms

Were the guards eager to talk to you about their experiences in the museum at night? NE: Both Joe and Kawal, the two warders we interviewed, were fantastic. We had an abundance of stories in the end and had to leave out some great stuff. Both were very keen to stress the unnerving feeling that patrolling such a large empty building in the middle of the night has upon you -- how they believed that the pictures started to come alive, how the eyes would follow you around the room. They told us they tried to get in and out of the Gallery's store rooms and basement as quickly as possible, because the coldness and stillness of those rooms amplified every little sound made by the water in the pipes or the soft whine of the dim fluorescent lighting. Joe in particular was fantastic at conveying that sense of apprehension, and at describing the feeling you get when you think you see shadows move out of the corner of your eye, and have to keep reassuring yourself that it's all just a trick of the mind

What are the challenges of making an audio production about deeply visual content? CF: It's really tricky. We have a little grace because we make two versions of the podcast –- audio-only and enhanced in which the audio is accompanied by a slideshow of images. Having that second option was really important to the National Gallery, as you can imagine, and means we can show lots of lingering details of their incredible paintings. But we always ask interviewees to be as visual and descriptive as possible because we're aware that around a third of our listeners download the audio-only version

Would this story work in any other medium besides audio? CF: I think The Brothers Quay have more than shown that it can work in film. If we've managed to capture even a whisker of the strangeness that's in The Phantom Museum , we'll have done well. But audio does have a huge advantage in that, as a medium, it's inherently disembodied and uncanny. Darkness and spectral voices are part of the experience -– particularly if you listen with your eyes closed or late at night in bed. And I love Neville's SFX because I think they demand that kind of concentration. They're so subtle, the audio equivalent of glimpsing movement out of the corner of your eye –- which again, is just right to describe the feeling of walking through the National Gallery at night

What do you hope listeners will take away from the monthly National Gallery podcast? CF: Elena and the team at the Gallery see the show both as a chance to make contact with art-lovers around the world who can't visit in person, and to invite those closer to home to pop in. So I hope it gives listeners a more personal relationship with the Gallery. There's a big commitment behind the podcast, both from the team at the National Gallery and at Antenna Audio. It's not viewed as a marketing add-on, but as a creative product in its own right, which, in practical terms, means we have a regular budget, a reasonable amount of freedom, and generous access behind the scenes. And we're also lucky to have two great colleagues to work with month on month -– Leah Kharibian and Miranda Hinkley, who present and conduct many of the interviews.