This impressive piece of photography equipment is the Nikon Nikkor 6mm f/2.8 - a lens first produced in 1970 for the Photokina trade show in Cologne, Germany. At the time is was crowned the "world's most extreme angle lens" with the ability to shoot 220º on a 24x36mm.
Even when it became available to the general public in 1972, it was still only available to special order, so anyone who has a spare £100,000 will be glad to know that Gray's of Westmister have spent six months tracking down one of the lenses from overseas.
The lens is in mint condition, uses 12 glass elements in nine groups and weighs 5.2kg. It has a minimum focussing distance of 25cm and features a slip-on front lens cap and is delivered in a rugged metal case.