The tunnel on the A3066 has been closed since the landslide on the hill above, caused by heavy rain and flash flooding on July 6 and 7 in which a month's average rainfall poured down in just 24 hours.
The collapse, which left the tunnel structurally damaged, was so severe that people took photographs of the dramatic scene without realising that a car lay buried beneath the mud. Mr Vaughan said it had shifted "several hundred tonnes of mud, water, brick and trees".
The families of Rosemary Snell and her companion had reported them missing last week, and gradually the police came to suspect what had happened.
"By the end of last week, those concerns were such that the police began scrutinising telephone records and their banking details, and it became clear that they had been in Beaminster on the weekend of July 7," Mr Vaughan said.
The car was only uncovered after heavy machinery was brought in on Monday night. "It wasn't obvious in any way, shape or form that a vehicle was there," he said.
- Independent