Two brothers are facing lengthy jail terms after a court heard they killed a wealthy banker who intervened in an attack on a "down and out" in a city centre.

A judge watched closed circuit television footage showing father-of-two Frank McGarahan, 45, collapsing after being repeatedly punched by former amateur boxers Tom Cowles, 22, and Ben, 21.

As chief operating officer of Barclays Wealth, Mr McGarahan was responsible for bringing 500 jobs to Glasgow as part of its investment in the Aurora building in Bothwell Street.

The brothers admitted manslaughter and were remanded in custody. They will be sentenced on June 26 and Mr Justice Saunders warned they would get "substantial" jail terms.

The Cowles appeared at Norwich Crown Court and denied murder. Mr Justice Saunders said deciding to accept a plea of guilty to manslaughter must have been difficult for Mr McGarahan's family and prosecuting lawyers - but added it was a "sensible" decision.

Mr McGarahan, his brother Kevin, and cousin Sean Ryan, both also in their 40s, had tried to stop a man being attacked by a gang, the court was told.

Prosecutor Mark Dennis, QC, said the three men had approached with "caution", shown no "aggressive intent" and had been attacked without provocation.

Mr McGarahan died after collapsing following the assault in Norwich around 3am last September 28.

"His death has destroyed us and ripped our family apart. He has left behind a wife and two young children who will never know their father," Kevin McGarahan told police.

"All we were trying to do was to help a man who was in trouble."

Mr Dennis said pipefitter Ben Cowles had "taken a run" and punched Frank McGarahan in the head before attacking Kevin McGarahan.

Builder Tom Cowles had then grabbed Frank McGarahan and punched him repeatedly - detectives said they counted 10 blows.

Mr McGarahan then "suddenly and dramatically" collapsed after being punched in the head again by Ben Cowles.

He never recovered consciousness and died in hospital the following day.

Ben Cowles also admitted assaulting Robertas Sinkevicius - the man described as being of a "down-and-out" appearance. Both brothers pleaded guilty to affray.