Flood has just remixed a track by Tom Jones. "I was given a choice from 20 songs, and I picked the one that stuck out by a mile, the only one worthy of doing anything with. It was a bottom-up production: re-recording it."

Such is the clout of this inconspicuous, anonymous and yet strangely ubiquitous workaholic. In the last year he's remixed for Patti Smith, Massive Attack, the Boo Radleys and the Cranes. He produces for Erasure, Nine Inch Nails and Depeche Mode; he worked alongside Brian Eno on U2's 'Zooropa', and he's just about to disappear into studioland until Christmas to work on the new PJ Harvey album. So what does he do on his day off?

It's the opening of the Museum of Synthesizer Technology and Flood is a modular-system fiddler of honour. On this particular day off - undoubtedly one of the few - he's talking production tips in the museum grounds, and we're trying to discover what defines 'his thing'...

"The more interviews I do," he says, "the less I want to quantify if, because I think really your thing - and that's not specific to me - is just instinctual. You refine it only by experience."

But what is it that you're aiming for when you thing something is not quite right?

"Quite often you're relying on your own personal judgment, your own likes and dislikes. You hear something and go, 'Okay, that spurs me on to thing, well, I'll try this.' Quite often you go in and it doesn't work out, so you have to try plan B. But you have to on instinct. Though it does help," he adds, "if there are people around going, 'Yeah, that sounds good.' It's so difficult when you try to quanitfy 'my thing' because there's no reason why I should like a Patti Smith song, a Tom Jones song, a Massive Attack song. I just know I like them, and they spur me on to be creative."

Flood's instinct has been fashioned by at least 16 years in the business, starting off as an engineer. According to muso legend it was his tea-spilling that earned him his nickname. In the 80's he worked with Soft Cell, Cabaret Voltaire, and The Associates, building up a reputation for a hard-edged approach.

"In all forms of music I get pissed off, for want of a better word, with people following fashion," he says. "If you get caught up with always looking behind, then you end up with what 90% of music is today - retro. Very, very few people are leading at all. I don't think they are challenging themselves."

So who were the production visionaires? "I tend to reflect on older people, like the Visconti stuff with Bowie and Bolan; I like Kraftwerk, but then I love Iggy Pop. I'm a poor mixed-up kid. "But then," he continues, "I try not to spend a lot of time listening to everybody around because there's so much mediocricty. I've spent a year working with Nitzer Ebb and NIN, plus those eclectic remixes, and now it's PJ Harvey, so that's how I keep my excitement up. What's to stop PJ Harvey sticking a guitar through a VCS3? Nothing. What's to stop Nitzer Ebb going for total rock-out guitars and drums against a full-on analogue sequencer? Nothing. So cross-fertilisation and trying different things is important. Yes, I know I'm known for harder-edged kinds of things, but it's not always the case. I think 'Zooropa' is a good example of the mix."

When it comes to inspiration, Flood has enormous respect for Eno who co-produced 'Zooropa'.

"I've had the chance to see how he works. When I was an engineer, I was asked to work on 'The Joshua Tree', and I did that working with Eno and Lanois, and it was just, like, 'here's the rule book - throw it away'. Everything you thought before was wrong."

"I like Trevor Horn, if only for his specific ideas. I dislike the fact that people know what I do, in the same way you hear a Trevor Horn production and you know it. That's what I've become. That's why I say you could put the remixes I've done over the past year back to back and then see if people can say it about me. The role of the producer is to carry the band, not to overtake it."

Flood illustrates another important point as he recalls how he felt after working on 'The Joshua Tree'. "I went to do the second Erasure album, and that was coming from premier rock to premier pop and realising the cross-fertilisation that can be accomplished between the two. It doesn't mean that you have to play the second verse riff sound on a synth: why can't you have that concept in a rock song, and vice versa? So that opened my eyes."

Half an hour before the start of this interview, Flood, Suede producer Ed Bueller and a couple of mates played a storming set on the museum's temporary NME (no microchip electronics) stage.

Flood has a moderate modular set-up of his own, which goes into the studio if the client is inclined to cross-pollinate. "If you do a remix, what's to stop you shoving a guitar through a ring modulator?" Flood asks rhetorically.

Is that a favourite sound then? "Not particularly. To be honest, I started off as a guitarist, and I'm quite as happy to play guitar as use synths. The most important thing about today was that it was totally live. We only played together for the first time 12 hours ago. We were able to prove that synths aren't just cold, anonymous, have to sound like the same thing; within the right framework, they can deliver much more."

One of Flood's most radical projects of late was Depeche Mode's 'Songs of Faith and Devotion'. The shift in direction was by mutual consent. "On 'Violator' they wanted to push into new territory, so I think that by me being new, some of the distance was made. With 'Songs..' they were in a much stronger position to change, so bring in the drum kit, and change the recording method."

How, exactly?

"Inception of the songs rather than pre-producing them; trying them out live in the studio; demos being far more stripped back so there's more room for experimentation. Things like cutting down the amount of time spent on the computer - in the end, I don't think we achieved as much of that as we could have done. Also, using organic instruments - God, I hate that term - like guitar and drums incorporated with synths, but not making it sound like a forced dovetail. The synth sounds are all theirs, but it's the way they react to different people. They get used to their sounds, then they sit next to someone new, and they say, 'Ooh, that's a good sound, but what if you do this? Or this? It's that interaction that's important."

Cross-fertilise, interact, experiment: expect a Tom Jones-PJ Harvey duet at Christmas.

Flood on Trent

Flood produced Trent Reznor's 'Downward Spiral', as well as earlier NIN tracks 'Head Like A Hole' and 'Terrible Lie' from 'Pretty Hate Machine', and most of the 'broken' EP.

"I first heard a set of demos for 'Pretty Hate Machine' before he was even signed, and they just blew me away - by far the best set of demos I've ever heard. They were good strong songs, not pop songs; then, on top of that, someone had spent a lot of care and attention on how the songs were represented musically. To me, that was the best of both worlds. So I played the demos for the first album and thought, 'Well, what do I have to do?' I was asked if I wanted to work on it, and I said 'totally'. Sometimes you hear something and you say, 'Sorry, I've just got to do that - I don't even care if it's just one song."

Some guidance was required, though. "There was a problem in the middle, the way it [Head Like A Hole] dropped down," he explains. "I think we changed the drum sounds, changed the feel, re-introduced backing vocals at the end. Encouragement was important: can we get any more out of the vocal? Bring it in a little bit earlier? It was a mutual respect thing, rather than storming in there and saying, 'Well we need to change that and that'. But really, 60-70% was there before we got into the studio."