Originally Posted By: Ian
We own and use a 'briefcase cooker':

Briefcase Cooker

£9-£10 here and Butane refills £1 each. Very easy and very safe to use. Also an additional gas ring in the kitchen when needed, Christmas dinner, big BBQ, cooking at the table, picnics.

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A large (huge) vacuum flask may be used as a slow cooker, Pre-warm, fill with rapidly boiling stew, seal and only open when ready to serve.

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I have found it easy to get large 3-4kWh computer UPSs for nothing. Companies often replace the whole thing rather than just rebattery every couple of years and throw out the old one!!!. I have the heating boiler wired to a standard plug which is simply plugged into the UPS which is then plugged into the wall. It will run our system for some days easily, either bridging the blackout or giving time to set up an alternative


I would be very doubtful indeed about the "briefcase cooker" linked to above.
Apparently they have a very poor safety record, with a number of explosions reported.
The failure mode is said to be leakage of the gas, which ignites and plays a flame over the gas cartridge which then explodes.
I prefer an LPG cooking ring with a large refillable cylinder that is a reasonable distance from the flame.