Down a salt mine

Driving a car off-road is always entertaining, but today was something quite extraordinary. Mercedes took us to the Winsford Rock Salt Mine, the main supplier of the salt that keeps Britain's roads safe in sub-zero winter conditions. Deep under the Cheshire countryside, the mine tunnels stretch for 130 miles.

Somehow they managed to take three of the new Mercedes GLA-class cars down into the mine, 550 feet below the surface - as deep as the Blackpool tower is high. Elf'n'safety rules meant that we had to dress up like Bob the Builder to descend to the depths, kitted with high-vis clothing, hard hats, ferociously bright lamps and emergency breathing gear. Everyone had an electronic tag to check in and out, so if anyone went missing they'd know. It took 90 seconds for the mineshaft lift to reach the bottom. Once there, we drove the cars on a circular subterranean off-road course marked out with dayglo arrows.

What an amazing experience! Some of the brightly-lit central spaces down there soar like a cathedral, while the miles of tunnels are dark and mysterious. It's no place for claustrophobics ...

Back on the surface we drove in the rainy Peak District and dodged the showers to photograph the cars. It was a long weary trip home, back down the M6 and M1 and round the M25, but what a day!