Until we zoomed past it on a train, en route to Watford, we never knew that London had a McVitie's biscuit factory — let alone that it churns out 180 tonnes of chocolate digestives daily.
Like Charlie in that Roald Dahl classic, we pined to get behind the gates, into this fantastical world of confectionery. Like Charlie, we were fortunate enough to find a golden ticket. Well, their press people got back to us.
"I was 15 stone when I came here," laughs Fraser Jones, Manufacturing Manager, as he leads us around the McVitie's factory.
You'd have thought that 20 years on the job would put you off the digestives, Hobnobs, Mini Cheddars, and various other iconic biscuits that are manufactured here (these days the beloved Jaffa Cake is made up in Manchester). Yet as we make our way around, Jones picks out a treat here, another there — sampling them for quality (we assume), as he imparts his biscuity nous to us, in a soft Welsh accent. Here is a man who loves his job.
We're taken to the top level of the factory, where 11 industrial mixers whirr away, filled with biscuit mix which, at this stage, resembles concrete being readied for a pour. "It's the same as when you make biscuits or cakes at home," says Jones, "just on a much bigger scale."
Computers control the (heavily guarded) ingredients these days, which are stored nearby in towering silos. But some of Harlesden's machinery dates back to the late 1950s — hulking great machines that recall the children's TV show Bertha. It makes you misty-eyed to think these are the same machines that were churning out the biscuits that first got our parents and grandparents hooked. Talk about heritage.
Built in 1902, Harlesden's McVitie's factory marked the expansion of the McVitie's empire, started by Robert McVitie, a skilled baker whose shop on Rose Street, Edinburgh proved a hit with the locals. Today, McVitie's has seven UK factories, and exports its wares as far as Australia (which is also its biggest export market).
The Harlesden factory's position — next to the canal and the railway — was ideal for shipping raw ingredients in, and finished biscuits out. Indeed, this industrial estate once thrummed with household brands, including Heinz. Jones takes pride in the fact McVitie's are still plugging away in the capital.
While you can't lick the wallpaper, or eat the hard hats at McVitie's, here and there, is a flicker of Wonka magic. Take the 'enrober' — the closest you'll get to a chocolate river — which lacquers the tops of digestives with sweet molten goodness. Then there's the corkscrew conveyor belt which spirals boxes of biscuits up into the ether. We wouldn't be surprised if today's eddies of fluffy snow outside were a permanent fairy tale fixture.
Then there's the stacking bay, wittily named Jenga. Usually inhabited by just one member of staff — plus a bank of computers — this space is ruled by orange ABB robot arms — performing hypnotic dances of industry. The packing bays are named after tube stations, and denoted in the iconic roundels — another hint at the fun that's had in this factory.
Though much of the process is automated now, the factory demands of team of 580 to keeping it running 362 days a year, round the clock.
Says Nina Sparks, Factory General Manager, "The women used to be in the packing hall and the men, production people. When I started here 20 years ago it was very much the same. Now we have women running the ovens.
"That was a 'man's job' at one point. It has changed." The factory also employs people from around 50 different nationalities.
So what does Sparks think makes something like the digestive — invented in 1892, and originally advertised as a digestive aid — so endearing?
"It's in the very fabric of society," says Sparks. "As a kid, that's what I used to have when we came home from school." Judging from some of the vintage ads on YouTube, she wasn't the only one to enjoy the biscuit as a humble, post-school treat.
Sparks' own biscuit of choice these days is the chocolate Hobnob, and she falls firmly into the category of 'don't dunk', though she acknowledges why people do it.
At an innovation centre in High Wycombe, a team works behind closed doors, dreaming up new styles of biscuits and cakes. "It's all top secret, with bits cordoned off," we're told. Perhaps the chocolate digestive's, or the Jaffa Cake's newest rival is being taste tested as we type. Food for thought.