Within these various categories, the day would decide a range of different championships, including the MSA British Hillclimb, MSA British Leaders and Midland Hillclimbing Championships. But first things first, a quick chin-wag with Matt Nicoll-Jones, founder and owner of Academy Motorsport.
Matt set up the company in 2005, but today, he's just signed off on the firm's third Aston Martin Vantage GT4, and runs the Academy race team which currently competes in the British GT and hopes to compete in Le Mans 24hr in the near future. Even more immediately, he'd just driven one of his GT4s up Shelsley, and he had a big smile on his face.
"We ran it on wets today, which was fun! On slicks, we'd have managed a time in the high twenties, but today was more about playing for the crowd and it would have been a little twitchy. To have been given the chance to drive here was brilliant. Shelsley is very special. I really admire those guys who were setting low 20-second runs," he said.
And what does a man who runs a race team drive day-to-day? Well, after watching a 15-plate Audi S8 put in a silly time given its size and weight, Matt looked nonplussed. "I'm not surprised in a way. I drive a V10 RS6 Avant. It's been hiked to around 700bhp. I think we managed to get 3.8sec to 60mph out of it."
Continuing around the paddock, I arrived at arguably the main event - the invitation class. Before me stood a row of cars that had competed at Shelsley across the decades, with vintage racers such as a Pilbeam MP58 and Chevron B25. One, in particular, wasn't so much vintage as ancient; a 1911 Sunbeam 16/20 with what appeared to be wicker baskets for seats.
Huge admiration has to go to the men who hustle these beautiful but potentially very painful cars up the course. With names such as Hickey Hickling, owner of the Sunbeam, and Basil Davenport, owner of a 1938 Spider II, you can picture them now. Even the cars' names meant business - take the 1922 Becke Powerplus, which was held together with the same device holding up my trousers. No-nonsense drivers, essentially, from a time before lattes.
Just as much bravery (and a degree of lunacy) is needed to win the day, though. The fastest car of the event was the brutally loud Gould GR16X, running a race-tuned 3.5 V8. At the hands of multiple event winners Alex Summers and Scott Moran, who shared the driving, it charged up the hill in a barely believable 23.05 seconds. It's jaw-dropping stuff.
Ultimately, though, Shelsley felt welcoming - like an event rather than a hard-and-fast competition, even if there was a competition going on. Watching dad climb into his single-seater, while mum and son number one pushed him to the start line with grandparents and daughters scrubbing the grass from the tyres, was a great experience.
It's a motorsport, like many others, that often involves the whole family. As we climbed the course and watched the cars slithering around the three main bends, it was obvious that for those 20-30 seconds, weeks of hard work were hanging in the balance. It's a superb day out, and I recommend it wholeheartedly.