Britain on Monday named Ken McCallum, a career spy who led the response to the attempted murder of Russian former double agent Sergei Skripal, as the new head of its MI5 domestic intelligence agency.
McCallum, who has worked in MI5 for 25 years, rose through the ranks working across the agency's main fronts from Northern Ireland to countering Islamist militants and ensuring the safety of the 2012 London Olympics.
Then, after former Russian double agent Skripal and his daughter Yulia were found poisoned with a Soviet-developed nerve agent known as "Novichok" in 2018, McCallum led the agency's response to the attempted murder, MI5 said.
"Our people - with our partners - strive to keep the country safe, and they always want to go the extra mile," McCallum said in a statement.
"Having devoted my working life to that team effort, it is a huge privilege now to be asked to lead it," he added.
Britain blamed Russia for the attack in which a British citizen died. Russia denied any role, though Western powers expelled dozens of Russian spies working under diplomatic cover.
Skripal, a former officer in Russian military intelligence (GRU), betrayed dozens of Russian agents to British intelligence.
Andrew Parker, who retires at the end of April, has led MI5 since 2013. He stayed on longer than is usual to ensure a stable transition during Britain's exit from the European Union which took place on Jan. 31.
Spies in Spotlight
During Parker's watch, MI5 had to contend with a spate of deadly militant attacks in the United Kingdom including the 2017 Manchester suicide bombing which killed 22 people, and attacks on Westminster and London Bridge the same year.
The Manchester suicide bomber, Salman Abedi, was known to the authorities but not under active investigation when he blew himself up in the foyer of the Manchester Arena after an Ariana Grande concert. A later inquiry said both MI5 and counter-terrorism police had missed chances to prevent the attack.
MI5, established in 1909 to counter German espionage ahead of World War One, is tasked with protecting British national security. Its main job is currently countering international terrorism though it is also a counter-intelligence agency.
It employs about 4,000 people.
MI5 said one of McCallum's top priorities was enabling the agency to seize the fast-moving opportunities provided by technology, including machine learning.
"Ken McCallum’s expertise and leadership will be crucial to ensuring that the Security Service remains agile and creative in the face of new and emerging threats to our security," said Mark Sedwill, the Cabinet Secretary.
He helped deepen MI5's partnerships with the MI6 foreign spy service and the GCHQ eavesdropping agency and has worked on secondment with the business ministry on digital issues as well as a non-executive director of the Nuclear Decomissioning Authority.
In 2017, he was appointed deputy director general of MI5 with responsibility for all of MI5's operational and investigative work.
McCallum grew up in Glasgow and has a degree in Mathematics from Glasgow University. He enjoys mountain hiking.