A BBC investigation has unearthed evidence that Islamic State (IS) agents were trying to recruit people in 2016 for an attack on central London.

In online messages sent to a BBC Inside Out reporter, an IS recruiter suggested attacks on two locations which were both targeted earlier this year.

The authorities were fully aware of the reporter's contact with the organisation.

Terror by Text: An Inside Out special airs on BBC One HD and BBC One London at 19:30 BST on Monday.