When I went to Download recently, I purchased some boil in the bag meals, thinking that these would be quick and easy alternatives to overpriced burgers. I had intended to take a Trangia stove, however these were not permitted on the site, so I bought two of these instead (I decided to buy two as this was cheaper than one plus refills).
The stoves were light weight, and easy to use for basic cooking with aluminium pans (not sure how well they would fare for cooking anything more serious). I found that the best way to use them was to start with one block, then a couple of minutes later, add another, and so on. This will allow the water to boil constantly for 5-10 minutes. I found that starting with 4 blocks meant that the water did not reach boiling before the blocks burnt out.