Jaguar Land Rover announced its biggest quarterly loss on Thursday after it was forced to take a £3.1bn write-down on the value of its investments as Chinese demand slumped. Britain’s largest car manufacturer, which is owned by India’s Tata Group, made a £3.4bn pre-tax loss in the last three months of 2018 as sales fell. It anticipates a loss for the financial year as a whole for the first time in a decade. Half of the £3.1bn non-cash charge was…