"Sounds simple. Isn't." Six brilliant hours in UK's most confusing race

I have not been overthinking any of it since an opportunity to race in the Birkett arrived.

John McGuinness of multiple Isle of Man TT-winning fame turns out to be too busy and I am not too proud to be mentioned as 'tbc' in the programme stepping into his shoes.

I'll be driving the 750MC's own Suzuki Swift Sport Challenge car, which I'll share with another TT and Dakar rider, James Hillier.

It's his first four-wheeled race but, well, he's raced at the Dakar and the TT, so he knows what he's doing.

We're in a team with two Honda Civic Type Rs, both front-runners in the 750 Club's Type R Trophy, a quite serious championship for quite serious machines, with airboxes that look like they could swallow a sandwich.

The Swift's mechanicals are, in contrast, pretty much standard, which will leave it as one of the slowest cars in the field.

The Hondas are much quicker and that puts us in Class A. A team with four Caterhams is in Class D. A team of four Clios is Class A too, so I'm not sure they're working them out according to overall speed, and I'm not really thinking about it.

I'm not sure anyone is taking it too seriously. Chef Tom Kerridge is racing in a Renault Clio and the most pressure anyone at the event is under is probably his team's caterer.

What I do know is that there are 67 teams, so outside of pit-lane handovers and breakdowns there will be that many cars out on circuit at a time. In recent years the Birkett has been held on Silverstone's 3.66-mile GP circuit, which is one of the few British tracks that will feel big enough for so many cars.

But such is the disparity in car speeds that I suspect it will be busy. I've raced in a Britcar 24-Hour race with around 60 cars in the field and that felt much busier than a Citroën C1 race with 99 cars all going roughly the same pace. At least it will be daylight all the way through.

And from a competition standpoint, the good thing about having a breakdown in this race is that if one car fails to proceed, the team can send out another once it has been recovered. So there should be 67 finishers.

The club's Swift Sport Challenge is a relatively new series, one of several start-up one-model trophies from the past few years.

Among the rather nice things about it in addition to its rather splendid logo is that the Swift Sport is a great fun car in the first place, and the modifications do nothing to dent that character.

The Swift is a small car, one of the more compact superminis on sale but by the time it's stripped out, it gets a race wheel and a race seat mounted low in the cabin, it actually feels quite big.

I think it's the low driving position and high window line that does it. But it's still road legal and registered one of the key draws of the series. It's not unusual, series organisers tell me, for racers to drive their car to the event and then home again.

There are single-make series where potential for crash damage would render that a risky operation, but the 750MC is a friendly club on and off track. Race entry fees are low.

You could, and people do, have a car, bring it to a handful of races a year and spend only a couple of grand a year doing it. Used cars can be £1500 and prepping them £6000-£7000.

I know that's still not the cheapest hobby in the world but there's not much better in racing circles, you don't have to have a support car, it will have resale value and the rest of the time you've got a Swift Sport for exciting trips to the shop.

The radio even still works in this one. I listen while waiting for my stints because it pays to be buckled up and ready during the previous driver's turn, just in case anything happens to them on circuit.

Communication is all by pit board and hand signal but I can see when a previous driver has been called in and get waved out as soon as they roll past my pit garage.

It's not just difficult to know where in the field I am: it's impossible to be sure because, while live timing in the garage shows the field with the theoretical weighting applied, the finishing order will be adjusted again after the event.

So once out on circuit, I just put my toe in and go about having a nice time driving the door handles off a Swift while not getting in anybody else's way.

And I have not had many better times driving a car. The Swift moves around a bit under braking, it turns keenly, I can feel it pitching a wheel into the air on the way into corners and it revs rather happily on the way out.

Karting excepted, I sometimes find that I most enjoy racing after the event, once the perilous bits are finished with. But not here, not now. I'm having a ball. We're not doing too badly, either, my teammates and I.

Deep into the final hour, the adjusted order has us running top five or thereabouts, and we have a Civic on circuit to keep up our lap speeds and keep the opposition behind.

Alas this is perhaps our undoing: the Swift doesn't spend quite enough time on circuit to avoid the adjudicators knocking us down a few spots, to seventh overall, rather than the podium finish we might have just squeezed.