I moved into my current flat last year, and one of the selling points for me was a lockable cupboard on the ground floor, which has sufficient space for several bikes. The lock is quite basic and the doors would not stop a determined thief for long, but at the very least it keeps my bikes out of sight. I'm considering buying another bike, and spending some money on it, so am looking at better security. I've considered a bike cage, but they're expensive, and may not fit in the cupboard. An option would be a ground anchor and hefty cable(s), such as:
http://securityforbikes.com/torc-ground-anchor.php
Any experiences, advice on options?