Fact: The 1997-spec McLaren F1 GTR Longtail is rare breed of race car that was made after homologation of three F1 GT street versions.

Let's run some numbers here to support that claim. There were only 106 McLaren F1s ever produced, 28 of which were F1 GTR race-going versions. Ten out of those 28 race cars were the 1997-spec Longtails, and one of them is on sale at Tom Hartley JNR in the UK.

And it's not just one of the ten McLaren F1 GTR Longtail units – it is the first of those ten, bearing chassis #19R.

Gallery: First McLaren F1 GTR Longtail for sale

The first 1997-spec F1 GTR Longtail was made as a development car, replacing the previous #10R that has already been sold. There were only two samples of these, the other one owned by renowned collector Nick Mason. However, this particular #19R F1 GTR Longtail was the first to have been converted to road-legal specifications, done by Lanzante and Gordon Murray Design.

Even better, if you're not up for its road-legal spec, the original parts will be sold as a package, including a dedicated book by Gordon Murray Design that documents the history of this rarity and its road-spec conversion.

Of course, this F1 GTR Longtail still carries its 6.0L BMW V12 engine that produces an air restrictor-controlled 600 bhp (447 kilowatts). The transmission is an X-Trac 6-speed sequential transmission.

And yes, as a Longtail this sample features heavy bodywork for an increased downforce with weight reduction down to 910 kilograms (2,006 pounds), although we think that has been increased a bit because of the road-spec conversion.