The unmanned machine will monitor hand tunnels dug by Victorian miners 150m below Alfriston and Friston.

South East Water wants to check water supplies are sufficient for the villages.

Trevor Muten, water resources manager, said there would no interruption to water supplies or danger to staff.

He said: 'A century or more ago, men would dig a well which often turned out to be dry.

'Then they excavated a small tunnel from it in search of water.

'This was a very hazardous operation because the miners would keep digging the tunnel until they came across sufficient water flowing through the rock.

'Often the water would break through and they would flee for their lives, leaving their tools behind them.'

The electric mini-submarine, with camera, has been lowered down special access wells.

South East Water wants to make sure the tunnels have not collapsed.
Rainfall fills the tunnels through chalk on the South Downs.