There's no legal requirement in private, domestic self-contained flats to have smoke alarms (of any kind!) although this fire just goes to show how important it is to have them anyway. The linked ones are great to alert everyone instantly, although if you just have the cheaper battery-only ones, they are far better than having nothing at all. If anyone needs advice or help on fitting them, I'm happy to help out (I'm a fire officer) - alternatively go to the LFB website - http://www.london-fire.gov.uk/SmokeAlarms.asp - where you can also arrange for a free home fire safety visit by the local firefighters and they will fit smoke alarms for you.