Spy Gareth Williams was laid to rest today in a service attended by the head of MI6.
Sir John Sawers made the journey from London to the small Bethel Methodist Chapel in Anglesey to support Mr Williams' family and represent the maths genius's colleagues who could not attend.
Sir John, the public face of the agency, took his place in the 115-year-old church through the front door - unlike a number of other spooks ushered into the building through a back door to protect their identities.
Mr Williams, 31, was on secondment at the Secret Intelligence Service from GCHQ in Cheltenham, when he was found dead last month.
His body was discovered trapped in a padlocked North Face holdall placed in the bath of his flat in Pimlico, London.
Mystery surrounds his death and police continue to investigate.
No trace of drugs or alcohol was found in the cycling enthusiast's body.
Outside church, when asked if the investigation would ever get to the bottom of what happened to Mr Williams, Sir John said it was not for him to say.
He insisted it was a police matter and said: "It has been a desperately sad period for the family since Gareth died.
"It has been very difficult for them and I wanted to be here today as the only public face of the Secret Intelligence Service.
"My deepest sympathies go to the family.
"Gareth was a hugely talented person and he was very modest and generous as well.
"He did really valuable work with us in the cause of national security."
In the church, tributes were led by Islwyn Williams, the headteacher of the code breaker and cipher specialist's primary school, Ysgol Morswyn.
Mr Williams said of all the children he taught, the spy made the strongest lasting impression and was academically brilliant.
The teacher applauded his pupil for transferring to secondary school at age 10 and passing his maths GCSE at age 13.
"He accomplished more in three short decades than the rest of us do in a lifetime," he said.
Tearful relatives followed Mr Williams's pine coloured coffin into church with his parents Ian and Ellen and sister Ceri, whose husband Chris Subbe also paid tribute to Mr Williams during the service.
The dead man's brother-in-law said he and his wife last saw him three months ago.
Mr Williams had taken the pair for tea at the Ritz hotel to celebrate their second wedding anniversary.
"As the sun was setting the world was ours for the taking," said Mr Subbe.
Mr Williams's parents issued a short statement saying: "Ellen, Ian, Ceri, Chris and all the family wish to thank everyone for all the sympathy and kindness shown to them in their bereavement."
Mr Williams was last seen alive eight days before his body was found.
CCTV showed him shopping at Harrods and at Holland Park tube station.
Police have refused to categorise his death as murder.
Mr Williams was days from completing a one-year secondment to the headquarters of the Secret Intelligence Service, MI6, in Vauxhall, London.
He was due to return to a rented flat in Cheltenham where Government Communications Headquarters, GCHQ, is based.
Mr Williams also worked for the United States National Security Agency and made regular trips to Washington DC and Fort Meade, near Baltimore.Reuse content