A relevant link:
https://www.gov.uk/police-powers-to-stop-and-search-your-rights
However that link fails to mention that there are some specific places, such as at airports, where police permanently have additional powers (under various pieces of legislation) and places where police are granted temporary powers under Section 47a of The Terrorism Act (2000) (Remedial) Order 2011. (Such temporary powers can only be granted by an officer holding the rank of Assistant Chief Constable or above and, if they're to remain in place for more than 48 hours, be further authorised by the Secretary of State). Despite the nominal 'temporary' status of such powers though, many places, such as all railway stations in the UK, were covered by them for many years (and might still be so for all I know - I can't find any definitive information on the issue).
It has to be remembered though that a police officer can't arrest anyone for anything (even murder) unless he has reason to believe that the suspect won't
voluntarily attend a police station. See here:
https://ibb.co/s2ZZ30H