With permanent visa, you are not allowed to be away from UK more than 2years. Basically you are supposed to live in UK.
What it you live in your own country and keep visiting UK every two years?
I heard that you would lose your visa if you did that. But I wonder how they will find it out.

I'm going to apply for permanent residence in May after working for 5 years with a work permit. But I lost my passport recently and will get a new passport. Using form NTLTOC, I can get a visa stamp on my new passport, I believe. In this case, Can I still apply for permanent visa in May? Don't I nee...