Waller was living in Munich when he met Guinness at an evening reception at the British Council back in 1985. "I asked him to play a cameo role but he said he was booked up for the next 18 months. I said 'What about tomorrow morning?' He was flying home at lunchtime but he agreed as long as he could read the script that night. His part didn't actually exist so I had to write it and then, overnight, find the location, hire cameras, crew and a vintage Rolls. We shot him in an underground car park. I shot the bloke he's talking to in a back yard in Moscow in 1993."
Waller, 36, has been a long time coming. A precocious film talent who began making Plasticine and drawn animation films on Super 8 at the age of nine, he seemed Boy Most Likely To when he left the National Film School in 1981 as its youngest ever graduate - at 20 a good 10 years younger than his peers. "I thought it wouldn't take long to make my feature film debut. But projects never happened."
He worked in Germany as an editor on TV films then began a successful career in music videos and commercials. So successful that in 1986 his tax accountant recommended he move to Monaco, where he used his money to finance Mute Witness, written two years earlier.
Originally he intended to shoot the film - about a mute girl locked overnight in a film studio witnessing the making of a snuff movie - in Munich masquerading as Chicago. Then he met a Russian dentist who suggested it could be shot much more cheaply in Moscow. Between them, Waller and the dentist got other investors and came up with the $2.2m budget.
"Moscow as a setting had great potential. The three main characters were American and it accentuated the feeling of danger, isolation and helplessness. Mosfilm studios were perfect as the location - they were run down and eerie yet they also had, for example, state of the art sound studios."
That was once the production actually got started. In pre-production, Waller first had to deal with his lead actress, Gina Bellman, dropping out with a kidney infection; a diphtheria epidemic in Mosow; and Russian customs holding his film equipment to ransom for $50,000 when it was flown in from Munich. The first day of shooting, Waller woke to the sound of explosions and machine-gun fire. Yeltsin had ordered the storming of the Russian parliament.
Filming finally began, under strict curfew, a week later. Then, enter the Russian mafia. "We were told by our Russian co-producers that we had to pay off three different mafia groups to allow us to shoot in peace. They were quoting prices more expensive than Hollywood. Contracts meant nothing - it was a question of bargaining on a daily basis - I could speak Russian fluently by the end of the four months."
Even so, Waller regards it as a "wonderful" experience. "There was an incredible amount of stress but I grew close to the team. And at the end, we got a deal we would never have got had people bought in on just a film pitch. Columbia Tri-Star, who bought the world rights to the film, had turned it down once as a script."
His next project is An American Werewolf in Paris, a tardy sequel to John Landis's 1981 hit. Other offers to direct are coming in. "They are very attractive, but I have yet to read a script which bowls me over. Although I've been busy and successful since leaving film school, if I measured my success on feature films alone then it has taken rather too long. So I want to be sure I get it right."
n 'Mute Witness' is screened at the LFF on 11 & 14 Nov, and opens in the UK in Jan