Plastic driving licences replaced paper versions in 1998. The rules say photos must be renewed every 10 years costing £17.50 or it becomes invalid and you could be slapped with a £1,000 fine.
Around 400,000 licences will expire this year and next, so check your licence now to see when you're due to update it with a new photo.

Thanks, Twee.

I seem to remember reading a while ago that the government know that very few people are aware of this but that they have no intention of reminding people.

Worrying...