Police have identified four of the 13 people killed by a bomb on the number 30 bus in Tavistock Square on Thursday.
Jamie Gordon and Philip Russell were on their way to work
Two of the dead were City worker Jamie Gordon, 30, of Enfield, north London, and finance manager Philip Stuart Russell, 28, of west London.
The families of two others do not want their names released until an inquest into the deaths opens on Wednesday.
Police said 11 victims of the attacks had now been positively identified, but only three have been named publicly.
On Monday Susan Levy, 53, from Hertfordshire, who was a Tube passenger, was the first person to be formally identified as a victim of the bombings.
Fifty two people have been confirmed to have died in Thursday's attacks.
The death toll is expected to rise, and 74 family liaison officers have been assigned to the relatives of those still missing.
Mr Gordon's family described him as a "kind, caring person who always put other people first".
He called his employers, independent financial advisers City Assets Management in Old Street, at 0942 BST on Thursday to say he was on a bus between Euston and King's Cross.
Five minutes later, the 30 bus travelling from Marble Arch to Hackney was blown apart by the fourth of Thursday's bombs.
The roof was torn off and nearby cars were also damaged.
His family's statement continued: "His great sense of humour and personable nature put him centre stage with family and friends. He loved life, but he didn't take it too seriously."
Mr Gordon's fiancée, Yvonne Nash, 30, an events marketing manager for mobile phone firm Orange, said he would not normally have taken that route into work from their home but had stayed at a friend's house on Wednesday night following a colleague's leaving party.
"He was very much in love with Yvonne and finally settling down with plans for a wedding and family.
"Jamie touched many people's lives and the response to this tragedy is overwhelming", they said.
Jamie, who had grown up in Zimbabwe, came from a large and close family and loved horse riding, skiing, playing the guitar and singing, the statement said.
Close friend, photographer Nicky Willcock, 31, who laid flowers close to the scene of the bus blast, said she had done so to support her friend Yvonne.
"On my card to both my friend and her boyfriend, I wrote that everyone feels this with them.
"London is the most vibrant and culturally diverse city on the planet, and if these terrorists were trying to divide us, they have failed."
Mr Russell called his employer in Moorgate at about 0930 BST on Thursday to say he was going to be late after being evacuated from Euston station.
Prime Minister Tony Blair has signed the official the book of condolences for victims of Thursday's bomb attacks, at the of the Greater London Authority headquarters
Philip Russell would have been 29 on Monday
He wrote: "With my deepest condolences for all those who lost their lives and for their families, who mourn, and with heartfelt admiration for London, the greatest capital city in the world".
Recovery efforts are continuing in the wreckage of a Tube train between King's Cross and Russell Square stations.
Metropolitan Police Commissioner Sir Ian Blair visited King's Cross on Monday to lay flowers and said officers would identify victims as quickly as possible, but warned the process could not be rushed.
"However terrible it is, we must take our time as we go through the identification process," he said.
The anti-terrorist hotline is also available on 0800 789 321.