By James Davey LONDON (Reuters) -One of Britain’s leading businessmen has criticised Prime Minister Boris Johnson’s government for reversing course on policy, including over anti-obesity measures, saying companies are more consistent. John Allan, the chairman of Britain’s biggest supermarket group Tesco, said he was talking in a personal capacity when he condemned last month’s decision by the government to delay new rules banning multi-buy deals on food and drink high in fat, salt, or sugar. “Unlike the government, you know, whose view is that having an idea and sticking with it for more than …