MI5

Three Chinese citizens - suspected to be spies posing as journalists - must leave Great Britain. This was reported by the Daily Telegraph with reference to a high-ranking government source in London.
The MI5 intelligence service uncovered the true identities of the three spies; the report continues. They had been working for the Chinese Ministry of State Security. According to the report, all three individuals claimed to "work for three different Chinese media agencies" and had entered the country in the past 12 months.
The MI5 page informing the current UK (England, Wales, Scotland, and Northern Ireland) threat level was changed to SEVERE. Also, the threat to Northern Ireland from Northern Ireland-related terrorism is SEVERE. SEVERE means an attack is highly likely. Just 1 level below the top one: critical.