The family of a missing student was given false hope he was alive when they were mistakenly told he had boarded his plane home to Ireland from London, an inquest has heard.
Patrick Halpin, 18, from Loughrea in Co Galway disappeared during a college trip to London in February.
Concerned friends went to police who began a missing person's inquiry and scoured CCTV footage from a West End nightspot.
Mr Halpin's body was found two days after he fell from the roof of a Burger King outlet after walking off in search of food during a night out in Leicester Square.
Coroner Angela Hodes concluded that the "tremendous sportsman" died accidentally.
She said a "cruel twist" was that as his worried family searched for clues as to his whereabouts, police were informed that he had got on his plane at Gatwick Airport.
Ms Hodes told the inquest at Westminster Coroners' Court: "It appears that due to the particular procedure in relation to the airline, the information that was given to Detective Sergeant Paul Stephens was incorrect, leading to him erroneously informing the family that Mr Halpin had checked on to his flight.
"This court will be writing to the relevant agencies to see what they can do about their procedures."
In a statement, Mr Halpin's family praised the role of social media in raising awareness of his disappearance, describing the response as "amazing".
They said the teenager would be "sadly missed" and thanked police for working "tirelessly".
The inquest heard that Mr Halpin, who was found with half the legal limit of alcohol for driving in his system, was "not excessively drunk".
As well as playing Gaelic football, hurling and volleyball, he was a brown belt in karate and a keen cyclist.
It was thought that this combined with his not being used to consuming large amounts of alcohol, meaning that he had been affected by what he had drunk.
Ms Hodes said CCTV footage from the Zoo Bar, where he had been out with friends on the night of 4 February, showed him "politely bumping" into people. He had been told to go and get some food to sober up.
Mr Halpin, who was visiting the city on a trip with Dublin City University, was never seen alive again.
It was not until police looked back at CCTV footage that they were able to trace his last movements and saw that he had walked into a nearby Burger King, gone through a staff door, up stairs and on to the roof.
His body was found on a lower section of the roof on the evening of 6 February.
In order to access the area that he fell from he would have had to walk several metres to a barrier, slide down a slope and climb down waste pipes or a chimney, the inquest heard.
A post-mortem examination concluded he died of severe brain injuries as a result of falling from height.
Mr Halpin, who was in his first year of studying actuaries, "loved maths" and singing and took part in many musicals with a youth theatre group, the hearing was told.
The family concluded: "Live your life like Patrick did, with a smile and a song."