I was just going off Mt.Gox policy as a guideline which dictates that they are obliged to do so for at least 5 years
https://mtgox.com/privacy_policy...
If Intersango are keeping information when they have no obligation to do so then they are just being awkward I suppose.
I highly doubt MtGox has an actual legal duty to do so since they are not regulated as a financial operator.
They can still comply with regulations they are not legally subjected to, and IMO it is a good thing since we all want the bitcoin trading industry to gain a better legal recognition. And the first step to do so is to honestly acknowledge that, as of today, we all operate in a completely gray area with high legal risk and uncertainty.