LONDON (Reuters) – Police have begun to interview witnesses as part of their investigation into alleged breaches of lockdown rules at gatherings in British Prime Minister Boris Johnson’s office and residence, the Metropolitan Police said on Monday. Police are investigating 12 gatherings held at Downing Street after an internal inquiry found Johnson’s staff had enjoyed alcohol-fuelled parties, with the British leader attending a few of the events himself. “Detectives investigating allegations of breaches of Covid-19 regulations in Downing Street and Whitehall have begun to interview people, as …