Today, standing in his office before a model of the design, he says: “I’ve always loved the way Portland stone buildings emerge out of what I see as the City’s deathly disease of greenish-grey glass. Our tower aims to combine the autumnal beauty of rust red with the bright white of spring.”

The matte Cor-Ten steel will absorb light, he says, while the white gloss will glint all the way to the top, using colour-changing paint at the upper levels to cap the tower with a sparkly rainbow headband. With its simple form, exposed structure and whiff of industrial engineering, 1 Undershaft has the air of a no-nonsense skyscraper more commonly found in Chicago or New York, only dressed up in a slightly prissy costume – or with extra English refinement, depending on how you see Parry’s penchant for decorative dressings.

Its silhouette is subtly tapered, he says, so its facades converge at an imaginary focal point 10 times its height – a learned nod to Edwin Lutyens’ Cenotaph memorial in Whitehall, whose planes meet at a projected spot 1,000ft in the air.

Parry won an invited competition a year ago – against David Chipperfield, David Walker and PLP – and has been working flat out ever since, ready to submit a planning application in January 2016. The client hoped to build an even taller tower, but restrictions from the Civil Aviation Authority set a maximum height over the City so planes don’t have to slalom between spires. It was also restrained by the City’s new approach to less exhibitionist silhouettes. Parry’s design was originally meant to be crowned with a pointy hat, like Cleopatra’s Needle or the Washington Monument, but the planners requested “a less demonstrative top. They didn’t want another overt shape.”