Very rare Jag E-Type Lightweight for sale

The Motorexpo in Canary Wharf will host the sale of "one of the most desirable E-Types to come to open market in recent years."

The 1963 Jaguar E-Type Lightweight No. 14 is extremely rare and has a very unusual history. Jaguar only made 12 Lightweight E-Type race cars, although as the name suggests, this one is number 14. How so?