Sesame plc purchased a computer system for £74,000 on January 1, 2017. It was depreciated based on a 7-year life and an £18,000 residual value. On January 1, 2019, Sesame revised these estimates to a total useful life of 4 years and a residual value of £10,000. Prepare Sesame's entry to record 2019 depreciation expense.