By Guy Faulconbridge
LONDON (Reuters) - The MI5 spy chief, who oversaw a safe Olympics and helped transform the Security Service's counter-terrorism operations in the wake of the 2005 London bombings, will step down next month.
Sir Jonathan Evans, appointed director general of the domestic intelligence service less than two years after the July 7 bombings, presided over an expansion anti-terrorism operations. There were no major attacks on his five-year watch.
"He has experienced the service evolving over the years and as director general has led the service through particularly challenging times of change and unrest, including the aftermath of the 7/7 bombings," said Theresa May, the home secretary.
"I would like to pay tribute to Sir Jonathan for the 33 years he has dedicated to the service," May told parliament.
A successor was not announced though local media have reported one of Evans's deputies who commands counter-terrorism operations could be appointed. MI5 chiefs, who were not publicly named until the 1990s, typically serve for about 5 years.
His successor's first big test is likely to be the Group of Eight meeting due to be held in Northern Ireland in June. An earlier G8 summit, held in Scotland in 2005, was overshadowed by the July 7 bombings on the London transport system.
Separately on Monday, a militant nationalist group in Northern Ireland said the hotel where G8 leaders are due to meet was the intended target of a bomb intercepted by Northern Irish police and defused last weekend.
The successor will also have to grapple with cost-cutting and public complacency about the threat from militants who security officials say have hatched at least one major plot a year since the September 11, 2001 attacks on the United States.
Evans, who joined MI5 - also known as the Security Service - in 1980 after graduating from Bristol University with a degree in classics, appeared in public only about once a year for a carefully worded speech about the threats to the realm.
At the service, Evans initially focused on the threat from Northern Irish militants in the 1980s. He was charged with directing international counter-terrorism operations just 10 days before the September 11 attacks.
He warned last year that al Qaeda militants were using the countries which toppled their leaders in the Arab Spring protests as bases to train radical Western youths for potential attacks on Britain.
British officials say one of the biggest threats is likely to come from a domestic cell of militants who have received training or support from al Qaeda in Afghanistan, Pakistan, Somalia or Yemen.
"In back rooms and in cars and on the streets of this country there is no shortage of individuals talking about wanting to mount terrorist attacks here," Evans said in June. "It is essential that we maintain pressure on al Qaeda."
Evans warned against complacency, quipping that when intelligence folk smell roses they look for the funeral.
MI5 employs about 3,800 people - up from 1,800 at the time of the attacks on the Twin Towers in New York.
Given the formidable task of helping secure the 2012 Olympics, the first Games hosted by a prominent partner in the U.S.-led coalition formed after the September 11 attacks, Evans helped keep the Games safe with a light touch.
"His tireless work helped ensure the delivery of a safe and successful Olympic and Paralympic Games last year. I commend and thank him for his invaluable contribution to public safety and national security," May said.
(Additional reporting by Andrew Osborn; Editing by Pravin Char)