Ben Nevis is the UK’s highest mountain and has just grown a metre taller – but don’t worry, it’s not down to a volcano exploding or an earthquake shifting the earth. It’s down to technology. Experts at the Ordnance Survey (OS), the country’s mapping agency, recently climbed to the top of the mountain and used the latest GPS equipment to resurvey the mountain. And the new official height is 1,345m and not 1,344m. The Scottish mountain was last surveyed in…