In one sense it’s a baptism of fire – in another, hardly at all. Meg O’Neill’s arrival as the first female chief executive of BP comes, in a sense, at an auspicious moment. Oil majors’ earnings are set for a significant windfall from the conflict in Iran, with those of BP and Shell forecast to see a combined £5bn this year – and that’s if the war is limited in timeframe. That cannot mask, though, the scale of the task facing O’Neill, who arrives from Australia’s Woodside Petroleum…