Every petrolheald loves a classic Porsche 911, even if they don’t like the brand itself. There is just something so inexplicably charming about an early 911 that makes it a must-have for every car collector – or anyone who can afford it, for that matter.

But buying a classic Porsche 911 is an art in itself and a tricky business. There are so many different models and variants available to choose from, not all of them original, and not all of them worth investing in.

So there is a need here for a classic Porsche 911 buyers’ guide, and it’s a need that’s now been addressed by the great Harry Metcalfe, a well-known car collector, the founder of Evo Magazine, and performance consultant for Jaguar Land Rover Special Operations division. In this video he gives you some general pointers on what to look for when choosing a classic 911, and also delivers a tour of two special models up for grabs at Silverstone Auctions, a 1972 2.4 S and 1991 964 RS:

Nick Whale, managing director of Silverstone Auctions, says: “It is a delight to be able to present these two iconic air-cooled 911s for sale, alongside many other important Porsches in the Silverstone Classic Sale this week. Condition, history and provenance are some of the most important factors to consider when buying a classic car – and indeed when selling one, too. These examples are testament to why I have enjoyed buying and selling the Porsche marque for many years.

“Harry has worked with us at Silverstone Auctions, since buying his Ferrari Testarossa at last years Silverstone Classic sale. He is a well-respected member of the classic car community and I am humbled that he could take the time to share a fraction of his knowledge in this video. I’m sure you’ll see a lot more from him, as well as a few more high-quality cars for sale in the future.”