Well, don't control data access in the UK then.
UK laws apply to UK companies and UK located information.
I wonder what would happen if you host your data or even just one half of a master key in a country where privacy still means something, Switzerland? They too can demand access if there is enough evidence of criminal activity (little known fact about Swiss bank secrecy - it's the bit the US tends to gloss over when they accuse Switzerland of "hiding" data), but (a) the Swiss require a proper warrant issue process instead of the weasely "I wanna" in the US/UK (especially since you're crossing borders) and (b) have demands in place to treat such disclosed information with the extra care it requires. The privilege of legally enforced access is limited to those investigating the case, and the data is destroyed if the claim proves to be without merit.
I'm not quite sure what your position is if you CAN provide access but it would have to go through the Swiss - you're then not violating the law, just making it hard to do so improperly (IANAL, of course).
In the UK, it appears that as soon as you have handed off your precious information (about, say, High Net Worth individuals or some celebrity) there is NO requirement imposed on police or government to treat that data as it should. Translated; if someone high up wants to ruin your business (or get a copy of your confidential information), all he needs is (a) a high friend in government, (b) a manufactured section 49 disclosure and (c) an "accident" involving "lost" CDs or memory sticks, leaving you to clean up the mess, and there will be almost no audit trail to follow back. Alternatively, the so obtained data gets handed to a fresh school leaver who can be socially engineered to hand it over for a bar of chocolate (I may be putting the "bar" too high here, har har).
Just to clarify: I have no problem with the concept of disclosure for proper purposes - I understand the need (I was in London during the IRA years). However, there is NO excuse for the absence of proper audit, accountability and independent checks preventing abuse. If there was even a glimmer of transparency in the system it would be OK, yet that has been scrupulously avoided - thus prompting the mistrust it deserves.
It's not the citizen who may or may not have something to hide, it's the government which must remain accountable. BTW, you have to prove your innocence here (in case you missed it). First the banks managed it (CHIP & PIN swaps liability), now the government. Wonderful.
Well, I have TBs of storage available, and at a pinch I can also vault hard disks externally - all you need is split key encryption and you're on your way. You disclose the UK part, they'll have to work on the Swiss part (as soon as they cross the Swiss border it becomes a Swiss judicial matter, you can't just wander into another country with some plods).
Happy to help (where it remains legal) - I saw this coming when RIPA was just in discussion..