According to Ars Technica:

New laws going into effect today in the United Kingdom make it a crime to refuse to decrypt almost any encrypted data requested by authorities as part of a criminal or terror investigation. Individuals who are believed to have the cryptographic keys necessary for such decryption will face up to 5 years in prison for failing to comply with police or military orders to hand over either the cryptographic keys, or the data in a decrypted form.