What lock?

for your pride and joy?

thinking Kryptonite D lock but then i've heard bad things (and some theiving gypsy stole my Zaskar a few years back and got through my Krypto cable lock, stold the bloody lock too)

what else is good (although i don't suppose you can really test them till someone tries to nick your bike)

Abus Granit
http://www.mandp.co.uk/productinfo/559075/Security/U-Locks/Abus

Or oxford magnum.

Whatever you buy make sure the locking mechanism locks both ends of the shackle and it has a pick proof lock

second the granit.

I have 3 of them as well as an oxford barrier and anchor.

I use a granit on my london commuter, and the others at home.

Cable locks are mince. D-lock if you want portable, big chian for home defence.

try to use 2 different types of lock,
D-lock and a heavy cable lock,
most thieves know/carry tools to disable only 1 type.

but if they have the tools and are pro's then more than likely your bike is history,

I tend not to ride anything flash about town,