On 26th February, the Home Office published new guidance containing information for competent authorities in EU Member States (excluding Denmark and Ireland) and in the UK about obtaining evidence within the UK or abroad to assist in criminal investigations or proceedings. The EIO replaces existing measures for requesting and sharing evidence for criminal investigations through Mutual Legal Assistance (MLA) between EU Member States.
Note that Gibraltar is the only British Overseas Territories which operates the EIO, but the EIO does not apply for assistance between Gibraltar and the UK.
https://www.gov.uk/guidance/european-investigation-orders-requests