Horner confessed his past as a trespasser when team bosses were asked to recall their first memories of the British Grand Prix venue.
At the time Senna was leading the world championship, and he would go on to secure his third title. Horner was a 17-year-old karter who would move into car racing the following year.
“One of my earliest memories coming here was back in , shortly after I passed my driving test in my pimped-up Volkswagen Beetle,” Horner explained.
“They used to have a Goodyear tyre test here in June, the month before the grand prix.
“As an aspiring young karting driver I managed to find a hole in a fence – I don’t know whether it’s still there, around the corner from Copse, go through the tunnel, there’s a hole in the fence there.
"I crawled through that, I managed to get into the pitlane, and tried to pretend like I looked like I should be there.
“I had a karting jacket on at the time and came face to face with Ayrton Senna. It was a huge moment for me, he was one of my heroes.
"He’d had an accident on a jet ski and so he wasn’t doing a lot of driving, but he noticed the kart logo I had on my jacket and started asking me about karting. I thought, ‘I can’t top that! This day cannot get any better.’”
In fact it did, for Horner subsequently had the chance to see Williams star Nigel Mansell up close.
“I managed to sneak through a garage and get to the front of the pitlane and Nigel was testing his Williams," continued Horner. "I managed to get into [the] garage, God knows how, and overhear Nigel. They were asking him what was preventing him going faster through Becketts.
“I remember him saying, ‘I’m struggling to line my eyes up with my eye-sockets, because we’re so fast through there!'
“So that was a huge memory for me, just topped the day off. Meeting Senna, then Mansell, and then driving home in my very flash Volkswagen Beetle.”