A couple returned from a weekend away to find a massive mine shaft had opened up almost on their doorstep. June and Larry Lockett, of Sandhills Park, Gunnislake, are now facing a bill of up to £50,000 to cap the mine. The couple could not even park their car on their driveway because council officials had cordoned off the shaft. Mrs Lockett, 69, said: 'A geology expert said it was a shaft. 'They dropped a rock down it and they never heard it reach the bottom. It's a vertical drop.' Retired bus driver Mr Lockett, 67, said: 'I'm worried about what's going to happen, whether they are going to find the shaft will come through into the bungalow or towards my garage or even into the road. They say it's my responsibility and I'll have to pay for it.' Surveys The properties at Sandhills Park were built three years ago by DEM Projects for developers Rusillion Properties. Chris Speed, of Rusillion, said he was unaware of any mine workings in the area. 'Mine surveys were carried out prior to us buying the land, the properties were constructed under the supervision of Caradon's planning department,' he said. Jerry Masters, head of operations and technical services at Caradon, said as far as he was aware, the shaft did not appear on any maps of the area. He said this was likely to indicate it dated from pre -1872, when it became law to record all mine workings. Mr Lockett said his neighbours were now concerned about their own homes.