If it's like that photo it could be anything emanating from the 'drop tanks'. From a quick read of the Pilots Operating Handbook for a Hawker Hunter (got to love the internet age) they operate as one would expect, they pump into the main tank, so it shouldn't be possible for a leak in a drop tank to result in a loss of wing tank fuel nor pump pressure as it's a balanced feeder apparently.
Whilst this accident could easily be the result of a loss of thrust, I'd agree with some of the other people saying he came out of the loop late. You don't need much power to escape from the loop as you've got low power at that stage anyway (as your airspeed will pick up on it's own due to the gravity). If I was going to speculate, I'd look at reasons as to why the loop was exited so late.