LONDON, July 23 (Reuters) - British retail sales resumed their post-lockdown recovery in June after a surprise fall in May, according to official data. Retail sales rose by 0.5% in June from May, the Office for National Statistics said. A Reuters poll of economists had pointed to a 0.4% month-on-month increase in retail sales volumes in June. (Reporting by David Milliken and William Schomberg) Our Standards: The Thomson Reuters Trust Principles.