Britain’s Prime Minister Boris Johnson must answer “serious questions” over his nomination of a Russian-born newspaper baron to the House of Lords, the Labour opposition said on Sunday after new media revelations. Longstanding speculation about Johnson’s friendship with Evgeny Lebedev – whose father was a KGB officer – has revived since Russia invaded Ukraine. The Sunday Times newspaper reported that Johnson was warned about granting a peerage to Lebedev two years ago by Britain’s foreign intelligence service MI6, but he pressed ahead anyway. The agency had flagged security concerns about the …