Artist Stephen Wiltshire draws the Shard from memory

Wiltshire spent Friday at the offices of Sellar, developers of the London Bridge skyscraper, where he created an image of the current state of the building site.

The drawing will be on display in Hay's Galleria for The Big Draw's Make Your Mark on the Future: from London Bridge to Tower Bridge event on Friday 22 and Saturay 23 October.

The Big Draw has now become the largest and most influential drawing campaign in the world, bringing thousands of people together for the hands-on experience of drawing.

London's Mayor Boris Johnson will launch Make Your Mark on the Future on Friday morning.

The two-day festival includes free events along the river from London Bridge to Tower Bridge celebrating London's changing skyline with architects, artists, archaeologists and cartoonists.

Participating organisations include Southwark Cathedral, HMS Belfast, Shunt and the Unicorn Theatre.

Stephen Wiltshire is a London-based artist with a particular talent for drawing lifelike, accurate representations of cities, sometimes after having only observed them briefly.

In 2008 he joined Tony Hart to officially open the Art House gallery at Cathedral School in Redcross Way.