Richard Whelan, 28, was knifed on Friday when he tried to stop an assailant pelting his partner with food.
Yesterday, friends said his family were "utterly devastated" by the loss of Mr Whelan, an events organiser - just weeks after one of his closest friends, Ciaran Cassidy was killed on 7 July.
"We can't take much more," said Ciaran's mother, Veronica, last night. She explained that the pair loved to go to Arsenal games together. "Richard was very quiet. My son was outgoing but they got on well. Richard was always welcome around here."
Steven Day was friends with Mr Whelan and Mr Cassidy. He said he last saw Mr Whelan when they attended Ciaran's funeral in Finsbury Park. Yesterday, the 32-year-old said: "They were close friends, good pals and he took it very badly.
"We said we would go out soon, in a couple of weeks at the beginning of the football season, to talk about Ciaran. Losing Ciaran was a terrible tragedy and now this. It is horrible.
"Richard loved his football and we would go to games and then go out for a meal. That's probably what kept our friendship going. He had been very shy but, over the past few years, he had become much more confident in himself and very easy going."
The trio had formed friendships working for Woolworths seven years ago. Mr Day remembered employing a very quiet 21-year-old as a Christmas temporary staff member.
He continued: "They were good times. It was always a good atmosphere and we were close friends who would go out in the evenings."
Mr Whelan and his girlfriend of several years had enjoyed a few after-work drinks on Friday night when they boarded a 43 bus in Islington, north London, shortly before 10pm.
As they climbed up to the top deck, they were unaware that a six-foot tall man in his twenties who got on with them would become his killer. The man, who police said had an afro up to three inches long but was wearing a hooded jacket, began pelting passengers with food and many disappeared downstairs rather than challenge him.
Mr Whelan, from Kentish Town, ignored the man until his girlfriend started getting hit with chips being thrown by the man.
Detective Chief Inspector John Macdonald said Mr Whelan stood up to remonstrate and was stabbed about six times, including once in the chest, as his girlfriend frantically tried to pull the assailant off, shouting for help.
The knifeman strode down the stairs as the seriously injured Mr Whelan and his girlfriend pursued him. The man disappeared up Holloway Road as his victim collapsed on the lower deck. He died a short while later at Whittington Hospital in Archway.
Mr Macdonald said: "His attacker is obviously carrying a knife around and he was prepared to use it once, so there is a risk he may do so again."
The officer explained that Mr Whelan's girlfriend was still too traumatised to talk to police, adding: "I think the worst thing about it is that the couple could have been anyone, any one of us on a night out."
Neighbours around the house where Mr Whelan lived with his father, Richard, remembered a quiet young man with a ready smile who had grown up there with his sisters Dolores and Teresa, having lost his mother to illness at the age of 12.
A friend, Michelle Greengrass, 39, said the close family were utterly devastated, adding: "His father is in his seventies and beside himself. Dee is inconsolable. He was very kind and would do anything for you. He was quite shy but once you got to know him he was really nice He was not the type to get into a row.
"It is so shocking. You get up in the morning, go to work, come home, have a row with someone and you're dead. You can't even defend yourself."Reuse content