An astonishing new advert is taking the world by storm. Hollywood rebel James Dean is walking the screen again in a new advert that imagines what his life would have been like had he not died in a car crash aged just 24.

Technology brings the Rebel Without A Cause star back to life -- and then ages him, showing a startlingly realistic version of what might have been. He is shown receiving a lifetime achievement Oscar, as a director, protesting against the Vietnam War, and as a rather Angelina Jolie-like humanitarian ambassador.

In the final scene he has a car accident in a Porsche Spyder -- just as in 1955 -- but this time, as the smoke clears, a slightly stunned Dean is shown drawing a deep, shocked breath -- very much alive.

The film, entitled ‘Legend’, finishes with the tagline: ‘Given more time, imagine the possibilities’.

It’s an advertisement for a South African investment company Allan Gray -- but it has taken film critics by storm.

The film was shot over 14 months, with a cast of 300 and a crew of 150. The actor who plays Dean, a mechanic from Cape Town named Des Erasmus, underwent two months of coaching for the part. A combination of make-up, prosthetics, body doubles and CG face replacement helped bring the legendary actor to life. The famous accident scene was shot using a replica 550 RSK Porsche Spyder -- one of just two available. Dean had owned his Spyder for just nine days before the fatal crash.