An ambitious mission to drill through Antarctic ice to a lake that has been sealed off for thousands of years has been cut short.

The British expedition was attempting to reach Lake Ellsworth, which lies over 3km (1.8 miles) below the ice, to see if it contained evidence of ancient life on Earth.

A technical problem meant that the two bore holes failed to connect and the project was suspended.

The BBC's science editor David Shukman explains what went wrong.