Richard Dyson, 38, and Simon Midgley, 32, who lived together in London, died in the blaze at the five-star Cameron House Hotel on the banks of Loch Lomond on December 18, 2017 while they were on a pre-Christmas break.
Richard, a TV producer, attended Wetherby High School and his parents, Roger and Val, still live in the town.
More than 200 guests were evacuated from the building, including a family of two adults and a child who were rescued by ladder and taken to hospital in Glasgow but later discharged.
Dumbarton Sheriff Court heard on Friday that the fire started after a night porter emptied ash and embers from a fuel fire into a polythene bag and placed it in a cupboard which contained combustibles including kindling and newspapers.
Cameron House Resort (Loch Lomond) Ltd, the owner and operator of the hotel, admitted failing to take the fire safety measures necessary to ensure the safety of employees and guests between January 14 2016 and December 18 2017.
It admitted two charges of breaching the Fire (Scotland) Act 2005.
Advocate depute Michael Meehan QC told the court: “On December 18, (porter) Christopher O’Malley removed ash and ember from the fire, put it in a bucket, emptied it into a plastic bag and put it in the concierge cupboard.
“As a result of the accused’s (Cameron House Hotel) failure to keep the cupboard free of combustibles, it still contained various combustibles including kindling and newspapers.
“The Scottish Fire and Rescue Service investigation determined that an ember or embers within the ashes ignited and fire spread to the kindling and other combustibles. From there it spread within the main building.”
About 70 firefighters fought the blaze at the main building of the hotel, which saw the roof collapse.
The court heard the hotel operator had been warned of the risks of keeping combustibles in the cupboard following a fire service audit in August 2017, and the general manager had then highlighted the issue to staff.
Cameron House Hotel admitted it failed to have in place safe systems of work in respect of the removal and disposal of ash and embers from the hotel’s solid fuel fires and maintenance and emptying of metal bins in the rear yard for storing ash and embers.
It also admitted it failed to keep cupboards containing potential ignition sources free of combustibles and failed to ensure employees were provided with the necessary instruction, training and supervision in respect of the safe removal and disposal of ash and embers from the hotel’s solid fuel fires.
The court heard a plastic bag was used to dispose of ashes on December 15 and again on December 18, the latter with tragic consequences.
A fire alarm sounded at 6.39am and Mr O’Malley and the night manager noticed smoke coming from the concierge cupboard where the bag of ash had been placed.
Mr Meehan said: “Mr O’Malley opened the cupboard door and flames immediately took hold and spread from there to the hallway.”
Mr O’Malley and other staff tried to fight the blaze with fire extinguishers but realised they would be unable to stop it spreading and dialled 999.
Post-mortem examinations concluded that the cause of death of Mr Midgley and Mr Dyson was “inhalation of smoke and fire gases due to hotel fire”.
Peter Gray QC, representing Cameron House, said the failings were not deliberate breaches but occurred “as a result of genuine errors”.
He said an absence of formal procedures for dealing with ashes and embers gave staff the opportunity to improvise.
Mr Gray said the “improper use” of a plastic bag was noted and the member of staff warned after the incident on December 15 and that it was “difficult to understand” why a plastic bag was used again on December 18.
He said: “I am instructed to extend my deepest sympathies from the accused to the families of Mr Midgley and Mr Dyson.
“Cameron House Hotel is one of the leading hotels in Scotland, it takes pride in its reputation and sets itself the highest standards in relation to all that it does and endeavours to ensure the safety of its guests.
“It takes its duties to ensure the safety of its guests extremely seriously.”
Sheriff William Gallacher deferred sentence until next Friday.