If London had to describe itself as a colour, what would it be? Seems like a trite question, huh? But, mark our words, it’s going to be a very important one for the nation’s design agencies this year. The race is on to create the winning logo for the 2012 games. It ain’t going to be black and white. So our question is apt.

Traditionally, it would seem, red is the colour. After all, what better symbolised the capital in the 20th Century than the omnipresent omnibuses, K2 phone boxes, Tube roundels and sturdy post boxes. Chelsea Pensioners, Beefeaters, Royal Guards. The red tiles of Ancient Londinium and the terra cotta facades of Albertopolis and Mayfair. London clay itself.

But there are other, more modern ways of looking at the city. From space, the town is a sickly yellow-green colour. At least if Google Earth is to be believed. Zoom in closer, and London’s many parks, trees and garden squares impart more verdant shades. (Not so very far from the Londonist background hue.) Then there’s the grey meets green, and tangerine of the A-Z. The blue of the Thames, Tower Bridge and Gherkin.

Black also has a claim: the door of number 10, the London smogs of yesteryear, black death, Blitz blackouts, chim-chimerney sweeps and Blackheath.

But there’s a new colour in town: step forward regal, imperial purple.

Cross Waterloo Bridge at night, and you’ll see what we mean. Tower 42 and Tate Modern are both topped with hazy lilac blue. Hungerford Foot Bridges and the NFT are similarly lit. But centre stage, in more ways than one, is the National Theatre, finally justifying its horrendous bulk with a stunning night coating of mauve illumination. And soon, Kings Reach Tower will be reclad in London’s new house-style palette.

So, take note, logo imagineers and mystery line painters. If you want London in one colour, free of racial and political complications, vibrant yet welcoming, look to the high-energy end of the spectrum. For 21st Century London is the colour of power and peony, of plums and claret.