Speaking at an event in London this lunchtime, the chancellor cited the Wall Street giant as an example of a bank that "manifestly" failed to appreciate how the City landscape had changed.
Unfortunately this revelation about the hippopotamus apparently contradicts the fossil record, which suggests that the hippopotamus is only a very distant relative of the whale, not an ancestor.
For example, some venoms are chemical-based, and others are bacteria-based, so they clearly had to have developed along different routes and may not be as closely related as we thought.
But the greening of the city and the improvement in public transport and other infrastructure were clearly appreciated by many of the city's residents.
The two months recently spent on an advanced management programme at Harvard Business School, consorting with chief executives, has obviously rubbed off on Lewis, who is fizzing with energy.