We think of the Porsche 911 as being the stalwart of the junior supercar world, but after 28 years and more than 10,000 sales, the Lotus Esprit in all its guises was probably the closest contender.

And this year marks half a century since it broke cover at the 1975 Paris motor show, where its radical Giorgetto Giugiaro-designed shape was revealed in production form for the first time.

Overseen by Colin Chapman and a small team from Hethel, the Esprit went on to be Lotus’s first proper Ferrari challenger. Its four-cylinder engine and initially meagre output were mitigated by a sublime chassis, a sub-900kg kerb weight and bar-raising mid-engined dynamics.

So it is only right that Lotus – or rather Classic Team Lotus – has seen fit to celebrate the Esprit’s 50th birthday at its annual Garden Party, held in the manicured gardens of East Carleton Manor, former home of the late Colin and Hazel Chapman and a stone’s throw from Lotus’s HQ.

Of all the 50 (of course) Esprits gathered on East Carleton Manor’s lawns, there are just a handful of S1 cars, the purest exponent of the original ‘Silver Car’ concept’s acutely wedge-shaped lines.

Giugiaro is seated near one, with his interpreter, and I ask about his relationship with Colin Chapman: was there a language barrier? Giugiaro smiles back and replies: “Drawing was our common language.”

Engines fire up behind us, and I turn to see a mouthwatering selection of Colin Chapman’s 1960s single-seat race cars being driven out on to the manor’s front drive.

There’s Jim Clark’s Type 18, Type 32B and Type 35, among a few others. Clive Chapman, Colin’s son, has just returned in one of them and I ask him why the Esprit is so important in Lotus folklore.

“Dad was always looking forward. He saw what other companies were doing and wanted to raise Lotus’s game,” he replies. “We had gone from the Elan to the Esprit, but this extraordinary car still had (the Elan’s) handling characteristics… so you had your foot in both camps.”

Wandering around the gathered Esprits gives you a measure of how Lotus sweated the model for all it was worth with, by my reckoning, 22 derivatives produced during its life – possibly even more.

As well as the S1s, all the models from different designers are represented – X180 (Peter Stevens), S4 (Julian Thomson) and last-of-line V8 (Russell Carr) – plus special editions like the black and gold Esprit JPS and blue, red and silver Esprit Essex, both referencing Lotus’s F1 ties.

And what do we find in the manor’s swimming pool? Naturally, James Bond’s Esprit sub – aka ‘Wet Nellie’ – from the 1977 film The Spy Who Loved Me. In fact, it’s what looks to be a half-scale model, with the actual full-sized prop at the poolside, in front of the Turbo Esprit from the 1981 Bond film For Your Eyes Only.

As I leave the event, heads are turned towards Giugiaro, who is now sitting in an S1 parked next to Lotus’s 2024 Theory 1 concept car.

In 50 years’ time, I only hope that car will prove as influential to Lotus’s future as the Esprit was in 1975.