Thanks for your thoughts. Before I splash out £65 on two new elements (one oven, one grill) is there anything I can do to test the other parts of the circuit? eg the oven fan, thermostat, timer, circuit board? I cannot carry out your suggested trip test as now I am getting no power to the elements (only the rear fan for a second or so as per point 2 in my previous email). I have a sneaking suspicion the thermostatmight be the problem but don't know how I can test this unit.
You're quite right, after several trips I stopped resetting the clock. Oven is currently running so maybe the element has dried out over the past couple of days and stopped shorting, so I think your moisture theory holds water (excuse the pun!). Thanks for your help.