MI5 boss: We do all we can, but can't stop everything

The head of MI5 has said the country continues to face one of the highest levels of threat from terrorism he has seen during his 34-year career.

Speaking in an interview with ITV News, Sir Andrew Parker warned terror activity is still coming thick and fast and can be difficult to detect, despite security services operating at a greater scale than ever before.

Indeed, although organisations like MI5 and the police now have more than 3,000 individuals in security cleared jobs across 500 live operations, Sir Andrew pointed out there will still be terrorists not known to them, which means not every plot can be foiled.

Rather than worrying about this, Sir Andrew said: "We put that energy into our operational work to be even stronger to do something about it."

Last month, the Queen carried out her first public visit to the intelligence agency, where she thanked agents for their tireless work to keep the country safe.