New policy ACRO referrals to criminal casework has been added to the Immigration Directorate Instructions at Chapter 36. This covers cases where a foreign national is arrested in the UK. An overseas criminal records check is to be carried out automatically. If any offences are revealed and any offence is sufficiently serious, deportation action from the UK will then be initiated.
It looks like the policy has existed in draft form for some time but is only now being finalised and published.