Gas cooker grill

It is probably the flame failure device(thermocouple)that is not getting hot enough when button held in to generate the current to hold the gas valve open it may just be out of line (bent?) from grill gas flame or it has failed

Were the gas rings alight at the same time as the grill issue? If they weren't could it be that the lid on the cooker wasn't fully upright meaning the safety device cut in? We had something very similar when we started motorhoming about 12 years  ago.  The lid was only very slightly off of completely upright but safety feature meant it had to be fully upright. Took a change of gas bottle which had hardly been used before a call to the dealer before we solved it. 

A trick shown to me by a caravan engineer when we had this problem is to remove the knob put a piece of thin piece card in the bottom of the hole in the knob replace it and try that, sometimes the shaft is not being pushed in far enough, if it works you could then wait to have it looked at during your next sevice and under warranty if doesn't contact your dealer.  

Sounds like the thermocouple to me. 

Been there ourselves, in my case I put a small ball of crunched up aluminium foil into the knob hole. Yes, the reason one of my hob burners would not hold a flame was the hob casing stopped the flame failure device being fully pushed in.

A few seconds test to see if that is or is not the OP's case.

I wonder how many of us have paid for a new thermocoupler to be fitted when this would have worked

I've had a similar problem FB and cured it by gently cleaning the thermocouple by brushing it with an old tooth brush. I assume it gets spashed with spitting sausages/bacon etc.

peedee

Thanks for the advice everyone. Before I take it to the dealers I'll have a go cleaning/straightening the thermocouple but what does it look like.

 Like one of these ..... general thermocouples ebay