Exclusive: Adrian Fulford will also examine wider national security vetting system after Foreign Office controversy

Guardian investigation uncovers decision by UK security officials to deny clearance before Mandelson took up role as US ambassador

Ministers and civil servants face scrutiny after revelation Foreign Office overruled vetting procedure for US ambassador appointment

Darren Jones says he has ordered an urgent review into news that the Foreign Office ignored security vetting advice

Exclusive: Adrian Fulford will also examine wider national security vetting system after Foreign Office controversy

Almost all officials working in Foreign Office HQ undergo process before gaining access to top secret material