Not some silly 'you have one minute to discuss who should take the money', but like how they did it on that gameshow Pokerface a few years ago.
Stand them by their buttons, tell them that there has to be absolute silence, explain that there'll be a 10 second countdown during which there is still to be no conferring, if either of them want to take the £50K and run, they press their button and it's theirs, if they don't by the end of the countdown then neither of them win it.
Skip to 6:55:
That'd be much more exciting methinks...