Department Of Social Scrutiny

I rather liked this:

UK DoSS : HMRC Security Breach

Notably:

1. You should, without delay, change your date of birth. This has the added advantage of enabling you to pick a more suitable star sign than the one you already have.

and

3. Instruct your bank to write to you in invisible ink, Icelandic runes or the secret code of the Puffin Club.

The tax forms are good too (and, sadly, almost indistinguishable from the real thing...)