LONDON (Reuters) – Britain banned all service sector exports to Russia on Wednesday and imposed sanctions on 63 individuals and organisations, its latest wave of measures to increase pressure on Moscow to reverse course and pull back from Ukraine. Prime Minister Boris Johnson has been a leading supporter of Ukraine since Russia invaded on Feb. 24, framing London’s sanctions against Moscow as a way of punishing President Vladimir Putin over a war the Russian leader describes as a “special operation” to denazify its neighbour. The measures, the government said, would cut off Russia’s access to B…