"It's a very long race," says the race director. "If you feel tired or unwell, please come in the pits - for your safety and everyone else's."
As usual, I ignore him. The British 24 Hours is a very long race. This, at 45 minutes, is practically a sprint.
It's been almost a year since I last visited Thruxton, and it's good to be back on a rare (for 2012) sunny summer's morning. Just like last year, I'm here primarily to get a bit of track time and assess my stamina ahead of the big race at Teesside in six weeks' time. I've been training hard and trying to shave a few kilos off my already skinny frame. It's hard work - I miss my naan bread - but I've lost over half a stone since the BRKC race at Teesside in May.
Thruxton's once-interminable safety briefing has mercifully been shortened, and I'm soon rediscovering this twisty, physical circuit. Unusually for a race billed as 'endurance', we're using the shorter version, which disappoints me - I've always preferred the flow of the full circuit with its hairpin and fast chicane. But no matter.
In the past couple of years I've sampled a dozen new rental kart fleets, and only Teesside's prokarts match the speed of Thruxton's single-engine Thunderkarts. It's eye-wateringly expensive, and no less prone to kart disparity than anywhere else, but the fundamentals are good. Having last raced at Birmingham, whose karts would be troubled by a well-driven Dodgem, the opening laps are something of a culture shock. As is the circuit. Thruxton eats drivers whole and spits out the bones. It's fast, bumpy, twisty, unrelenting. And fast.
After weeks of rain, the circuit is short of grip, with lingering damp patches in a couple of places and no rubber whatsoever. As the flag falls at the end of the fifteen minute qualifying session I'm pleased to see my name at the top of the leaderboard, but the time, at 50.8 seconds, is very slow. I've done a 49.1 here in the past.
On reflection, it's probably a good thing that grip levels are poor. Forty-eight hours ago I was laid low with an upset stomach, every joint from neck to toes aching. I felt fine this morning, but an unnatural fatigue has crept in after just fifteen laps. I'm not sure if the karts are new - they look the same - but I don't remember the wheelbases being so short. I'm uncomfortably close to the steering-wheel, which adds to the muscle power needed to turn it.
With nearly half a second in hand I'm expecting to pull away from the field - as long as I can make a good start. As the lights blink green I'm away well and lead comfortably by the end of the first lap. But I'm wary of faster drivers whose pace was hidden in qualifying. I've sprung the odd surprise myself from lowly grid positions in the past.
But no challenge materialises. I pull away at over half a second a lap, and soon realise that the circuit and the kart pose the biggest threat to my win. Thruxton is anti-clockwise, and on the short configuration in particular you spend virtually all of the lap turning left. In my weakened state, the workrate saps me quickly, and by half distance I'm in serious trouble. My seat insert isn't quite big enough for these XXL-size seats, and I'm sliding around more than usual; the short wheelbase and relentless right-biased load push my injured right ankle - still not recovered from a skiing injury - into a painfully twisted position on the throttle pedal.
Thruxton has an LED information board at the start/finish line. If you know where to look, you can read off your lap time and laps completed as you pass. I've no idea how far behind me the second-placed driver is, but I'd guess at 12 seconds; I slow a little to give my body a break, watching his laptimes and trying to match his pace. The backmarkers make it difficult, and I do myself no favours with an over-ambitious passing attempt that costs me five seconds.
By 45 laps I can barely hold the wheel but am still in front and still lapping relatively consistently. My optimistic inner voice tells me I still have a decent lead, and that I'll make the flag without crashing or passing out. I hope it's right, try to stem the rising bile in my throat, and focus on the next corner.
51 laps. I'm steering whole sections of the circuit with my left index finger hooked through the bottom spoke of the wheel. My entire body is numb aside from my churning guts and blazing right ankle. I'm watching the startline marshal like a hawk, praying for the chequered flag.
At 53 laps, it's waving, and I can honestly say I've never been more relieved to see it. I even manage to lift a hand in salute.
I accept my winner's medal with a mix of satisfaction and consternation. What should have been straightforward was anything but, and I'm pleased to have prevailed. But unwell or not, I'm not happy with my overall condition. In six weeks' time I'll have to withstand six hours at the wheel, in three 2-hour stints. Teesside's long, flowing layout is nothing like as brutal as Thruxton's, but there's work to do before I'm ready.
Last year I was left disappointed with my performance after a variety of problems and insufficient preparation. This year, I and the rest of the British 24 Hours team - captain Alex Vangeen, Lee Jones and newcomer Lewis Tindall - are quietly determined to make up for 2011's disappointment, when we lost third place to a kart issue in the dying minutes of the race.
It's going to be an almighty fight at the sharp end, and we have every intention of being part of it. First practice starts on Friday 24 August.
Watch this space.