Sir Olly has since defended his role in the process, saying that the government’s vetting processes must “remain absolutely confidential”.
He previously told MPs that he had not seen the documentation from UK Security Vetting (UKSV), the government’s in-house vetting unit, containing their vetting assessment of Lord Mandelson.
He said that instead, he was given an oral briefing, during which he was told the vetting agency considered Mandelson to be a “borderline case”, but that the Foreign Office may wish to grant clearance with “appropriate risk management”.
Announcing Sir Olly’s decision to take legal action, the FDA said in a statement that the decision to sack him from the Foreign Office had been based on a “grievous misunderstanding” of government vetting procedures.
“Rather than being under a duty to tell ministers about the process leading up to the vetting decision, Olly was under an obligation not to,” it added. “Not only was there no fair procedure involved in his dismissal, there was no process at all.”
The union also said it would seek to argue that Sir Keir lacked the the legal authority to dismiss Sir Olly, who was also head of the UK’s diplomatic service.
Sir Olly, who was appointed to the Foreign Office job in early 2025, has held a clutch of senior civil service roles and was previously the government’s lead official during Brexit negotiations with the EU.
In a statement, he said he was bringing legal action “reluctantly” and it would have been unnecessary if the prime minister had “simply apologised for his mistake and made amends for the distress and cost it has caused me and my family”.
