Coverage as listed by whom?
I'm with O2. Their coverage map show "Good indoors and outdoors" for 2G around my house. There is no coverage inside and outside is too poor to make a call.
Back when I used to live near Salisbury Plain, we'd regularly check coverage maps to try to get any signal at all. Orange used to claim full coverage. They had exactly zero coverage. I just checked with a relative and they now claim "excellent" 3G coverage inside and out. There is still exactly no coverage, inside or out.
So what's the point of asking the operators when they outright lie about it?