LONDON, Sept 30 (Reuters) - Britain's economy shrank by a record 19.8% in the second quarter of 2020 when COVID-19 lockdown measures were in force, a slightly smaller decline than an initial estimate of a 20.4% fall in output, official figures showed on Wednesday.

Output during the three months to the end of June was 21.5% lower than a year earlier, the Office for National Statistics said. (Reporting by David Milliken; editing by Michael Holden)