It's safe to say this was a good day for the very lucky owner.

The first example of the McLaren MSO HS has been delivered to its incredibly lucky owner, and Youtuber Seen Through Glass was there to witness the occasion.

Developed and built by McLaren Special Operations (MSO), the HS is the most extreme iteration of the British supercar maker’s Super Series. Details on it are scarce, but it is believed to be powered by a 678 horsepower (506 kilowatts) version of the 3.8-liter, twin-turbo V8 engine. That should translate to a 0 to 60 miles-per-hour (0 to 100 kilometers-per-hour) time in the very low three-second range, if not high twos.

Still, that’s about the same kind of performance as the existing 675LT. But what sets the HS apart is huge amount of downforce it generates. Thanks to its knife-edge splitters, turning vanes, and P1 GTR-inspired rear wing, it reportedly produces a huge 485 pounds (220 kilograms) of downforce at 150 mph (240 km/h). That’s not too far off what a GT3 race car develops.

The owner here, Tom, previously owned a MSO-fettled 650S and asked if they could cook up something more like the McLaren GT3 race car. It seems like he didn’t much persuasion to part with (a lot of) his money once he’d been told about the HS. Tom’s car is chassis seven of the 25 that will be built, but is thought to be the first to have been handed over to the owner.

Incidentally, this video confirms that the HS has been sold to individual owners - there were suggestions that all 25 has been commissioned by a single buyer. Tom also confirms that the color and trim specified for each is completely different.

The 1000 675LT owners probably won't be too happy about the existence of the HS, as many of them bought their car on the understanding it would be the rarest, most extreme series-production Super Series car there will ever be. Since the HS is not finished on the production line, you can argue about whether it actually is a series production car or not. Either way, it will be a bone of contention.

Anyway, the HS looks like an astonishing machine. But can McLaren take the Super Series platform even further?