Speaking at a business conference in southern France on Sunday, Thiam recalled a visit to a school in Tower Hamlets where he found out that around half of the children only ate once a day. "That's something I had seen in Ivory Coast," he said.
Thiam added that a more redistributive tax structure could improve education for those at the lowest end of the economic spectrum.
"Something must be done at the national level so there aren't so many people left behind that the result of a national, democratic vote gives a result which is bad for the country in the medium term," he said.
But the former head of insurance giant Prudential questioned whether Remain campaigners would be prepared to pay more tax.
"I was watching the march in London on Saturday, which I welcome. But I would have liked to say to them: 'how many of you would accept to pay more taxes?'
"It's all well and good to have big signs and protest against the 'Leave' vote. But it would be another story if you started having a discussion about creating more solidarity," he said.