Medics recovered kebab meat the "size of a golf ball" from David Clark's airway, after he collapsed on a train at Silverdale station on his way home from the Lancaster FC v Farsley Celtic match on March 2, 2019.
Nicola Cavin, 22, of Market Street, Grange, and her brother David Noble, 32, of Main Street, Grange - who were returning from a day out in Blackpool - had known Mr Clark for around five years.
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The defendants and Cavin's boyfriend, Daniel Shepherd, had boarded the service earlier at Preston after going to Blackpool for the day, and the men sat with them.
It is alleged Mr Clark fell asleep and that the siblings pushed food into his mouth.
Police and paramedics were called to Silverdale railway station shortly before 9.30pm after Mr Clark collapsed onboard.
Several witnesses caught up in the chaotic scene gave evidence in the case.
Paramedics retrieved meat the size of a golf ball, which had been blocking Mr Clark's airway and further pieces of meat were removed from his throat at the hospital.
Tragically he died at 10.10am the next day, with a post mortem examination concluding he had choked to death.
The duo denied his manslaughter and have been on trial at the new Nightingale Court at Preston North End's football ground.
Prosecuting, Ian Unsworth QC, had argued the force feeding of Mr Clark in the manner which it happened was an assault.
The court heard Mr Noble had also told officers a similar thing had happened at the Uplands Hotel in Grange when he began to choke while watching an Ireland and England rugby game.
According to Mr Clark's widow, Susan, it was a problem that had existed for at least a year.
The Honorary Recorder of Preston, Judge Robert Altham, adjourned their sentencing to a date to be set and ordered a pre sentence report for both of them.
He thanked the jury for their work in the trial, which has lasted more than two weeks.
Both defendants were granted unconditional bail.
BTP investigating officer DS Gemma Jones said: “This is an incredibly tragic case and we send our heartfelt sympathies to the family of the victim David Clark.
“We are pleased that the case has finally been brought to a conclusion.”
Detective Chief Inspector Steve May added: “This was an unusual and highly complex legal case and I commend the courage of those witnesses who came forward and provided statements and those who attended court to give evidence.
“The dignity and composure of Mr Clarks’ family has been exemplary throughout and I hope that they can take some comfort in the knowledge that justice has been done.
“Our investigative team deserve mention for their consistent and thorough work to see this case brought to its conclusion.”
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