Walker didn't leave that night. Instead, he sat transfixed by the chorus, as they performed to a packed theatre in London's West End, reeling out tracks like Jimi Hendrix's
Purple Haze
.
"I started to hear all these lyrics that I thought I knew, in a completely fresh way.
"The ironies were just so powerful," says Walker as he recalls one man - who he now knows to be 88-year-old Len Fontaine, notorious for forgetting his lines - singing the acid-rock classic.
"He's not singing about drugs but what it's like to be old and forget everything."
As the couple left the theatre that night, both were struck by a similar thought - to make a film about the chorus. A rock opera about old age.
That was more than two years ago. Today, the documentary
Young@Heart
has become a surprise hit - growing from a 50-minute made-for-TV special, to a feature-length cinematic release, screening in theatres around the world.
While Walker was always intrigued by the group's story, it wasn't until he began editing the film he realised they were on to something special.
"My commissioning editor walked into the cutting room to watch some of it and laughed and cried all the way through a very long cut. And then asked, 'is there any more?'
"Other people started coming in and we had to keep boxes of Kleenex in the cutting room because people would always cry at certain moments. People began bringing cups of tea in and they wouldn't go away," he laughs.
When the original 50-minute doco screened on Britain's More4 - a small digital channel affiliated with Channel4 - the network's internet server broke down as viewers flooded the system with emails and feedback.
It was a surprising response to an idea Walker had originally written off as a long shot.
In fact, Walker and Sally were so doubtful the commission would go ahead, they never approached the chorus before pitching the idea to Channel4.
As it turned out, the commissioning editor loved the idea and greenlit the project immediately.
"We walked out of there and looked at each other and went 'how the hell are we going to make this film?'. We hadn't got Bob Cilman's permission at that point. We hadn't persuaded them, we'd got nothing. We'd got a commission based on nothing."
Cilman is the group's dedicated musical director and founder of the Young at Heart chorus. Formed in 1982, the chorus is Cilman's pride and passion - but the music buff had no desire to be documented by Walker. Or anyone else, for that matter.
"We didn't realise there were at least 20 other companies in Britain that were also trying to get the story," explains Walker. "We were in competition with everything - from little companies like ours all the way up to the BBC."
It was only as their breakfast meeting - which Walker describes as "absolutely ghastly" - was drawing to a close that Sally captured Cilman's attention when she asked if the group had ever made a music video. After all, she queried, they are rock musicians. Isn't that what they do?
As Cilman's eyes lit up, shrugging off the disinterested glaze of the previous hour, Walker realised they had found the chink in his armour.
"I said, 'Instead of just having a straightforward narrative documentary, why don't we break out of that reality and narrative from time to time and hit the audience with music videos?' And that's when he started to get excited."
While getting Cilman on board was initially a struggle, the chorus members were only to happy to be filmed.
"They're all essentially exhibitionist people," explains Walker. "What kind of person in their 70s or 80s joins a chorus to sing all over the world if they're not exhibitionists?"
The real challenge of the film - one that Walker was completely unprepared for - was two members of the choir passing away during filming.
Walker had always planned to discuss death in the film, along with other "taboo" subjects of old age, including sex, sickness and loneliness. But he never expected to address it so directly.
Though it is a difficult subject to discuss, Walker is the first to admit the deaths made the film what it is today.
"The deaths hit us really hard. They were really difficult things to deal with. But you and I wouldn't be having this conversation if they hadn't happened in the film.
"That's the awful truth. It's because that happened that the film took on a whole new dimension."
Walker pauses, before adding somberly: "That is not to say that it wasn't the most difficult professional problem I've ever faced."
It was also a blow for the couple on a personal level, as they had become close to the chorus throughout their Stateside visit. "We got to know them really well. I've never been in the situation where you actually talk to somebody one minute about his fears of death and a week later you see them in their coffin with the lid open."
But life is full of sudden changes, says Walker. One minute you can be laughing with someone, the next they fall down the stairs and die. It's something that has long fascinated Walker, who has always edited his films to switch suddenly from pathos to humour.
"I think that resonates with people as a truth," he explains.
Ultimately, though, Walker thinks the film's success lies with the people it observes.
"I'm proud of what I did with the film and I think it's a good film. I'd like to think that other people think it's a good film too. But I think it's power goes beyond that.
"It's got a visceral connection with something that is much bigger than the film itself," he says.
"People are identifying and connecting with it because they are connecting with people they know. It reminds them of other people, whether it's their own family or parents, or even themselves."
Watch the trailer for Young@Heart below:
LOWDOWN
Who:
Stephen Walker, doco maker
What:
Young@Heart, heartbreaking, uplifting documentary about a choir of senior citizens who sing rock songs - their way
When:
Opens in cinemas nationwide, October 16
The hitlist:
The songs covered by the chorus include Road to Nowhere (Talking Heads), Fix You (Coldplay), Schizophrenia (Sonic Youth), Should I Stay or Should I Go (the Clash), I Feel Good (James Brown), Purple Haze (Jimi Hendrix), Yes We Can Can (Allen Toussaint)
