A specialist unit created by the British domestic counterintelligence and security agency MI5 to get inside the heads" of terrorists has helped foil seven attacks in the past year. The Behavioural Science Unit at Thames House, the headquarters of MI5 [establishes] whether people flagged as potential threats are "talkers" or "walkers" - those who simply boast or those who are preparing to act. Research by MI5 shows that more than 60 per cent of so-called lone wolves unwittingly provide clues that they are preparing to strike. The BSU's work involves picking up signs of such changing behaviour. Neil, an Arabic and Norwegian speaker who has worked for the unit for six years, said ... his team is passed intelligence by officers that is gleaned from a network of informants and the public. The BSU then looks for signs of unusual activity. The BSU team pays close attention to "lone-actor" terrorists. The number of experts working in the BSU, which was created in 2004, has more than doubled since ... 2013. "We deal with probabilities and that is the nature of our work," said Neil, [adding that] some of those they profiled lied to themselves about their intention and the ultimate aim was to persuade them to abandon their radical ideology. He said the assumption that many extremists had mental health problems was wrong. "Only 2 per cent of members of terrorist organisations suffer from mental health problems, compared with an average of up to 30 per cent of members of the public," Neil said.