So far, there appears to have been no official statement from the authorities about the circumstances leading to Miranda's detention though The Guardian notes that:
The Metropolitan police said Miranda had been lawfully detained under the Terrorism Act and later released. "Holding and properly using intelligence gained from such stops is a key part of fighting crime, pursuing offenders and protecting the public," it said in a statement.
Jack of Kent has set out a strong argument that the detention may have been unlawful. At this stage, it is not actually possible to say in the absence of knowledge about the reasons behind the decision to detain Miranda and the actual interview to which he was subjected.
Schedule 7 does not require
reasonable suspicion and the only requirement appears to be that the detention must be for the purpose of determining whether he appears to be a person falling within section 40(1)(b). On that basis, anyone travelling could be subjected to this power because all the authorities need say is - 'We wanted to see if he or she came within section 40(1)(b).' Of course, the Act is concerned with 'terrorism' and one might expect the authorities to have some reason connected to investigation of terrorism for detaining a particular individual even if, in the strict letter of the law, they do not need any suspicion that the person detained is actually within section 40(1)(b).
This is, in fact, the case since Examining Officers are supposed to operate within the Code of Practice - Examining Officers under the Terrorism Act 2000.
Code of Practice: