The concept has no aero aids, he reveals, the low tail is "something to think about" and the side-opening tailgate will go as it's not practical enough. "However," he adds, "as a designer, you learn with concepts not to over-promise."
"It's a Jaguar," confirms Jaguar brand director Adrian Hallmark. Yes, and also the most eagerly anticipated new Jaguar in decades.
Sports car sales may not be huge - the total market was only around 65,000 units last year - but the effect they have is enormous. "Nobody can get their head around what a sports car can do for your image," says Hallmark. The power of the segment is way beyond what its sales suggest. This is a vital car.
It knows it, too. "This is not trial and error," states Hallmark when asked why the time is now right for the F-Type. "We have taken it very seriously. We know it has a position."
Which is? A two-seat sports car that carries forward Jaguar's experience in a sector that, back in the 1950s, it virtually defined. Even the name deliberately references this. F-Type has been chosen, says Hallmark, "in the spirit of the C-, D- and E-types - the cars that, from a sporting and performance perspective, defined the brand credentials for more than 60 years."
Stated competitors (it'll be priced from around £55,000) include the Mercedes SL, the Porsche 911, and "lower-priced cars from those rivals" (think Boxster, Cayman, SLK AMG). Even so, Jaguar is not seeking to emulate them, but to create its own clear position: "The Jaguar will have a different character - it will be a true sports car."
As for what this means dynamically, Hallmark is clear. "Performance and character should start where the XKR-S finishes in terms of precision, agility, responsiveness, even if it has less pure horsepower than the 550hp RS."
The F-Type will also demonstrate Jaguar's trademark 'duality'. It will, says Jaguar, work equally well cruiser and focused sports car.
There will be four powertains and, although no technical details are being revealed (no more news on just what that wailing Nurburgring test car is, then - although the rumourmill suggests a V6 derived from Jaguar's 5.0-litre V8...), Hallmark says one powertrain will match the quoted performance figures of the C-X16: 180mph-plus, 0-60mph in under five seconds.
The trick hybrid setup, complete with push-to-pass button, is also an option, but not at first.
The C-X16 will be built at Castle Bromwich upon a full aluminium monocoque which Hallmark promises will be lightweight. Jaguar has form here so the mistakes of past (see our F-Type development history below) will not be repeated.
Jaguar is, however, starting with the convertible rather than the coupe. Start off engineering it as a convertible and you can build in all the necessary rigidity: this means the open-top car will be lighter and better than if it were a conversion - while the coupe will benefit from a platform even stiffer than it may otherwise have had.
It won't have a retractable hardtop either. If you ask why not, you quickly sense Callum doesn't like them. They jar with the Jaguar design philosophy, they take up space, the benefits in refinement are never fully realised and "they move the weight distribution dramatically to the rear". Fabric it is, then.
So is it the new E-Type? Callum has previously rolled his eyes at this question, but Hallmark makes Jaguar's position clear. "The name 'F-Type' tells the right story. We are NOT doing the E-Type, we are doing our own thing."
Jaguar wants the F-Type to be the logical progression from the E-Type rather than a revival of it. Indeed, Jaguar tested 30-40 names: for both 'traditional' and 'progressive' potential buyers, F-Type worked.
"A Jaguar with an alpha-type name should always be our most extreme sports car." From what Hallmark and Callum are promising, the F-Type will be just that.
Callum in particular appears confident: "I've been waiting 50 years to do this. You don't have to explain this car ... it speaks for itself."
From what we've heard so far, the ingredients are there: "very focused" XKR-S 'plus' dynamics, C-X16 looks, sub-911 prices... Here's hoping Callum is right: nobody wants to be disappointed by the F-Type.
Jaguar F-Type: three decades in the making...
Spring 1980: 'F-Type' project begins, using the platform of the XJ40
July 1982: Two models, codenamed XJ41 (coupe) and XJ42 (convertible) are signed off for production
March 1986: Initial target launch date (later revised to late 1988 due to delays with XJ40)
1987: Project reviewed
1988: XJ41 and XJ42 mules are sent to customer clinics for appraisals
1989: Ford buys Jaguar. Launches review of all projects in development: finds XJ41/42 are late and massively overweight
March 1990: Project is cancelled
1998: XK180 revealed, a radical 450hp two-seat roadster designed by Jaguar Styling's Keith Helfet
2001: Jaguar F-Type concept is revealed and later confirmed for production: target is 25k cars a year, with a target price from £30,000-£40,000. Scheduled launch date is 2004. Design started by Keith Helfet and finished by Ian Callum.
May 2002: F-Type project is halted
September 2011: Jaguar C-X16 concept is revealed at the Frankfurt motor show
April 2012: Jaguar F-Type is confirmed for production, with a launch date of summer 2013