Bentley's long-awaited SUV, the oddly named Bentayga, arrives later this year, but already the Crewe firm is lining up its next model.

"We need to do the analysis early, so when the SUV is executed the engineers can jump to the next product," Bentley boss Wolfgang Duerheimer told me. By "the analysis" he means deciding what sort of car it will be. The decision will be within the next year and a half.

There are two options, Durheimer explains. First, and most intriguingly, a fifth stand-alone model, to augment the Continental, Flying Spur, Mulsanne and Bentayga. The other option is a new derivative, just as the GTC convertible is a derivative of the Continental GT.

"We haven't decided yet." Duerheimer says. "But we're doing design work and testing those ideas with market research."

So what are those ideas? He won't be specific. Of course not, at this stage. But he lays down some tantalising clues. First, it won't sell for less than the £150k that's a realistic starting price for a Continental GT. "We're not thinking of a cheaper car. A Bentley will always be exclusive. It's not easy to get there, it's special to own one."

I remind Durheimer of a conversation back in 2012. He'd said that, after the SUV, he wanted to do a proper sports-car Bentley. He'd even added that a design had already been done.

Yes he says, he'd still like to. "There is the possibility of a smaller, lighter, sportier car. But not cheaper. We'll decide within 18 months."

But no sooner has Durheimer said it than he runs away from the idea, because he hints it would be a commercial mistake. The seemingly unstoppable march of the off-road crossovers is why. "The growing segment is SUVs. Convertibles are going down. Sports cars are going down. Saloons too."

So despite the success of Bentley's racing programme, with 19 cars contesting GT3 races worldwide, my reading of Duerheimer's clues is that the next Bentley after the Bentayga won't be a sports car. It'll be a coupe version of the Bentayga. But we won't see it until at least 2019...