The Liberal senator, whose dissenting report the federal government is relying on to hose down calls for a royal commission on Commonwealth Bank, did not turn up to a crucial hearing at which victims of the bank's financial planning scandal gave evidence.

Official Hansard transcripts show David Bushby, who was deputy chairman of the inquiry committee, did not attend on April 10 this year, when it also heard from bank whistleblower Jeff Morris, CBA executives and Australian Securities and Investments Commission officials.

Senator Bushby, regarded in Canberra as a friend of Finance Minister Mathias Cormann, also headed a smaller Senate inquiry that gave the thumbs-up to the government's roll-back of protection for consumers of financial advice.