RJH,
Yup, had my last GS nicked from outside my house, quiet street with no through traffic in Putney a month or so back.
Only myself to blame though, like you thought BMWs didn't get nicked!!
A disc lock seems to be the absolute minimum, we can hardly blame the police if we aren't taking "sensible precautions", though it sounds like you're getting good co-op.
Am dreading my next premium...
A few years back, I actually saw a guy riding my modern Triumph in the opposite direction 24 hours after it was stolen!! I gave chase, sweeney stylee, on my aged Bonneville, which actually went better over the speed humps (Steve McQueen stylee natch)
I eventually cornered the little t*at down a dead end, so he jumps off (thus damaging tank, sidepanels, exhaust etc etc) and legs it into a block of flats I'm pretty sure he lived in. Adrenalin subsided I called the coppers and awaited justice.
Police didn't give a monkeys, just told me I was lucky to get it back..
Lucky I bought it as a write off!!
Good luck