In June 2020, The Office for National Statistics released their Gross domestic product (GDP) report for April 2020. They calculated that GDP fell by 10.4% in the three months to April. This was directly caused by the UK government’s policy of lockdown.
https://www.ons.gov.uk/economy/grossdomesticproductgdp/bulletins/gdpmonthlyestimateuk/april2020