"Phew, so the buggers can't make me disclose Pa$$W0rd1 as my key"
Actually they can, and have been able to since 2000...
Regulation of Investigatory Powers Act 2000 part III (RIPA 3) gives the UK power to authorities to compel the disclosure of encryption keys or decryption of encrypted data by way of a Section 49 Notice. A suspect instructed to disclose keys can be prevented from telling anyone else about it, outside of their legal representative. Refusal to comply can result in a maximum sentence of two years imprisonment, or five years in cases involving national security or child indecency.
 Amended by Terrorism Act 2006 enacted 2006-03-30
 Amended by Policing and Crime Act 2009 enacted 2010-01-25