BP’s pipes in Alaska might be leaking like a sieve, but its coffers are nice and healthy. North Slope crude oil closed above $70 a barrel for the first time on Wednesday – on the back of concerns about Iran and tensions in Nigeria. It was only in May 2004 that the price hit $40 a barrel for the first time. Five months later it topped $50. In August 2005 it broke $60. Now it’s beyond $70. Any bets where it will stop?