LONDON (Reuters) - Britain’s opposition Labour Party has caught up with the governing Conservatives for the first time since Boris Johnson became Prime Minister in July last year, a YouGov opinion poll showed. Data released late on Friday showed the Conservatives and Labour both on 40% support, based on online polling of 1,618 adults conducted on Sept. 16 and Sept. 17. A previous YouGov poll on Sept. 9 showed the Conservatives on 42% and Labour on 37%. This is the first time YouGov, one of Britain’s main polling organisations, has shown Labour level with the Conservatives since May 2019, just before Theresa May said she would resign as prime minister and while Jeremy Corbyn still led Labour. A poll by Opinium on Aug. 30 also showed the two parties level. Johnson became prime minister in July last year and in December won the Conservatives their largest election victory since 1987, gaining an 80 seat majority which is likely to keep them in power until at least 2024. However Johnson’s popularity has fallen since December, due largely to growing public concern about his government’s handling of the coronavirus pandemic. Faced with a choice between Johnson and Labour’s new leader Keir Starmer - a former chief prosecutor who succeeded Corbyn in April - 35% of those polled said they preferred Starmer, while 30% favoured Johnson. Labour begins its annual party conference this weekend, while the Conservatives hold theirs from Oct. 3-6.