It emerged last night that police are investigating passengers' reports that the tram, packed with commuters travelling to east Croydon, nearly came off the tracks a week earlier at the same spot.
On a Go Fund Me page to raise money for his funeral, his brother said: "There are absolutely no words that can describe the true hurt and pain that our whole family is in right now". "He had an absolute heart of gold and would do anything for anybody".
Mr Smith said officers were investigating "a number of factors". Smith was engaged to his Lithuanian partner, Indre Novikovaite, with whom he has a young son.
"Maybe, if we had said something last week when it happened, this wouldn't have happened".
Dorota Rynkiewicz, 35, Philip Seary, 57, and 19-year-old Dane Chinnery have also been named as victims of the crash.
Barbara Dumbleton, a family friend, said the teenager "always had a smile on his face. he was absolutely lovely". "He said he thinks he blacked out". "[It's] so devastating how something like this can cause so much damage".
Tom Dale, who was travelling on the tram with Mr Chinnery, told Sky News: "I remember looking over, I was standing up and Dane was sitting listening to his music". "It was like walking out of a war zone", he said.
Friends and family clapped for one minute as they thought about those who had lost their lives in the derailment, ending by singing: "They're one of our own".
Croydon University Hospital said all remaining 38 people it had been treating had been discharged.
A group of up to 100 people on Saturday marched down the road carrying banners, flags and flowers to the spot where hundreds of bouquets had already been laid for the victims of the derailing in Croydon, south London. "Injuries have ranged from cuts and bruises to lacerations and crush injuries", he said.
The Guardian reports that, although the deceased have not been formally identified by police at this time, Mark Smith and two others were revealed on networking platforms by those who knew them, and had knowledge of them being on the Croydon rail at the time of its derailment.
Deputy Chief Constable Adrian Hanstock said: "After liaison with the coroner, we can confirm that at least seven people have lost their lives as a result of this incident".
"Mr Rogers, who said the incident left him "petrified", added: "(The crash) brought it back because we could have been on that tram".
It was thought to have been travelling at 40mph in a 12mph limit. Anyone who was on the tram, or travels or works on it regularly, is asked to contact them via their website.
The tram driver, a 42-year-old man, from Beckenham, was released on bail after being arrested on suspicion of manslaughter.
The packed two-car tram was heading to East Croydon when it overturned near Sandilands station at 6.10am yesterday.