Best house alarm for efficacy and value?

[Soylent Green]

We are looking to update our house alarm and would like to hear which companies people have used and whether they would recommend. Yes, I know this is a lazy approach rather than getting lots of quotes, but if someone else has already done the donkey work and wishes to share...

[apbremer]

We installed an alarm system from Guardian Alarms in Croydon. They maintain it and are always courteous and efficient. Never had any problems worth mentioning. We are linked in to two neighbourly key holders and, in extremis, the police. No idea about competitiveness but I think that are all much of a muchness.

[sheff]

We used Wickham, as have neighbours and found them to be great.