Dom Joly: I need a large glass of merlot with my jelly bean chaser

Napa Valley is no place for kids. It's California's wine country and my children, being only seven and 11, are not hugely into wine. I wandered into the Welcome Centre and asked a kindly looking lady behind a desk made of wine barrels what there was for kids to do.

"Kids? Well ... nothing really." This didn't look good. "Nothing?" I pleaded, desperately. She stopped for a second, shallow in thought. "Well, there is the jelly bean factory." We were saved. What could be better for kids than a visit to a jelly bean factory? It would be like going on a Willy Wonka tour and immediately make me dad of the year. Within five minutes we were in the car and on our way. Finding the place was not difficult: I just tapped in No 1 Jelly Bean Lane into the sat-nav. In the car park a HUGE inflatable jelly bean sat waving hello to my, by now, hyperventilating kids. Walking into the foyer we were greeted by the sight of a huge portrait of ex-president Ronald Reagan ... made from jelly beans.

As Governor of California, only 20 minutes away in Sacramento, Reagan gave up smoking and replaced his addiction with jelly beans. He used to say: "You can tell a lot about a fella's character by whether he picks out all of one colour or just grabs a handful." Quite what you could tell remains lost in time but it's clear that jelly beans played an important role in Ronnie's life. Towards the end of his governorship he remarked: "Some political figures have endured in history as lions or conquerors or something equally impressive. It's a little frightening to think California history might record us as jelly beans." Whatever that means.

Back in the factory, we set off on our guided tour. First, we had to put on really embarrassing paper hats that made us look like camp sailors. Then we were taken through a room containing more jelly bean "art". My particular favourite was the recently completed wedding portrait of the Duke and Duchess of Cambridge. It captured them perfectly, especially in the use of the Root Beer bean for Kate Middleton's purple dress.

A bored Latino guide took us along glassed-in walkways above the almost entirely mechanical manufacturing process. Robot arms performed simple, monotonous manoeuvres over and over again. It was all a little more industrial than we'd been hoping for – a bit like a car-manufacturing plant. If I had been in charge I definitely would have hired some little people and dressed them up as Oompa Loompas. They wouldn't have to do any work, just arse about on the factory floor doing tumbles and playing leap-frog. It would give the tour a little colour. I suggested this to the tour guide but he seemed surprisingly offended by my thoughts.

At every stage of the production, the guide would produce a sample box of beans and hand one out to each person using a special "single bean" scoop. Since we were watching millions and millions of the things being made every minute beneath us, this seemed remarkably stingy. When I pointed this out to the gentleman, he suggested that I might like to leave the tour.

We ended up in the huge gift shop where everything that is possible to make jelly bean-related was on sale. There were jelly bean flip-flops, umbrellas, memory sticks, Frisbees. I was a bit jelly beaned out. I could have sworn we even tried jelly beans in Dog Food and Pencil Shavings flavours. In fact, it was a very weird day out, and the joys of Napa and bountiful supplies of wine never seemed so appealing.