From the link above
A passenger who had just got off the plane told the BBC the pilot had informed passengers after landing that he had diverted to Stansted because of threats. The passenger, named by the BBC as Mr Munsif, said two men had been handcuffed on board and removed.
"We landed safely and then he announced that they had some kind of threat from someone and that's why he landed the plane," the passenger said, speaking by telephone.