The family of a "gifted and talented" student who disappeared during a college trip to London was given false hope he was alive when they were mistakenly told he had boarded his plane home to Ireland, an inquest has heard.
In fact Patrick Halpin, 18, from Loughrea, County Galway, had plunged from the roof of a Burger King outlet after walking off in search of food during a night out in Leicester Square.
His body was not found until two days' later after his concerned friends went to police who launched a missing person's inquiry and scoured CCTV footage from the West End nightspot.
Concluding that the "tremendous sportsman" died accidentally, Coroner Angela Hodes 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".
It added that 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 and it was thought that this combined with his not being used to consuming large amounts of alcohol, meant 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 his friends on the night of February 4, showed him "politely bumping" into people and he had been told to go and get some food to sober up.
Mr Halpin, who was visiting the capital 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 February 6.
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 statement concluded: "Live your life like Patrick did, with a smile and a song."