Principal shooting on Terminator: Salvation has now finished and director McG says it's all down to creating the post apocalyptic world in post (apocalyptic? - Ed) production.

McG: "It feels like the responsibility of any Terminator film to reinvent the wheel of effects with every outing.

"The first movie was a stunning achievement in animatronics and practical effects from Stan Winston.

"The second film brought us liquid metal, which was a true revolution in the effects world. Robert Patrick's (T-1000) head coming apart and putting itself back together again looks as good today as ever.

"We want the patina of the machines to be dirty and heavy and perfectly realistic - that's why we built so much practically with Stan Winston. But at some point the effects kick in and like any Terminator fan, Charlie wants his mind blown.

"There's one sequence in particular where we're trying to achieve something that's never been done before. I don't want to talk about it because we haven't been successful yet... But we're working on it.

"Most importantly, Christian and Sam bring power to the roles of John Connor and Marcus Wright. This is a story of two destinies colliding. Connor is part of a resistance comprised of the ethnicities that make up the globe.

"This film is so much more that just Los Angeles. It reflects the global crisis of man, all of man versus machine.

The sci-fi blockbuster stars Christian Bale, Sam Worthington, Anton Yelchin, Bryce Dallas Howard, and Helena Bonham Carter and hits UK cinemas on June 9th next year.