A documentary about the life and political career of the late Brian Lenihan jnr discloses the difficult relationship he had with Bertie Ahern and the limitations his lack of expertise in finance placed on him during the economic and bank collapse in 2008.

Lenihan, who died in 2011, is featured in the first of the Legacy series, which looks at three national personalities who each shaped Irish life in different ways during their lifetimes.

The documentary examines how his role in government affected the economics and politics of Ireland and assesses the loss of his leadership potential to Fianna Fáil.

Former taoiseach Bertie Ahern suggests that Lenihan’s intellect was not matched with an appetite for grind. However, Ahern is unstinting in his praise of the sacrifice Lenihan made when his terminal illness struck: “At times I felt he was even more focused as his whole life was about his illness and his job. His mind was crystal clear, sharp as a razor.”

Central Bank governor Patrick Honohan said that Lenihan did not have the background to really appreciate the risks with the banks. However, he added that he was quick to try to grapple with the emerging crisis.