Well done on getting out and not blanking, gents.
Paul, I've found that using gas appliances outdoors in cold temperatures causes them some issues.
Using my portable gas cooker on the Club Open in December a couple of years ago killed it, and similarly using a gas powered soldering iron outside in cold weather killed that.
When I say 'killed', I mean that the cooker struggled to cook the bacon for the butties at the time and the next time I went to use the cooker (in warmer weather) it simply would not light. I experienced the same thing with the soldering iron (no, not trying to cook bacon with it...)
I fixed them both by taking them apart and putting them back to gether again- although nothing out of the ordinary was found with either. The piezo start on the cooker never recovered- not sure if that was coincidence but a gas barbeque lighter replaced that part. I tested this effect on the soldering iron by using it on purpose in cold weather and found the same thing happened.
It's as if something 'waxes up' somewhere between the cylinder and the jets. I believe that this is one reason why moutaineers and other outdoor types prefer the performance of liquid fuel stoves (Coleman, Trangia etc) in cold temperatures.
You may want to try your cooker before you are desperate for a butty!