The Public Administration Committee held a one-off evidence session to consider the issue of Tory party deputy chairman Lord Ashcroft's tax status and donations on 18 March 2010.
Baroness Dean of Fylde - a member of the Lords vetting panel which considered Lord Ashcroft's peerage - told the committee that in her view commitments on tax and residency given at the time "were not carried through".
When asked whether the House of Lords Scrutiny Committee was deceived, she said: "It looks like the commitments were not carried through."
Sir Hayden Phillips - the civil servant who oversaw the agreement about Lord Ashcroft's arrangements - said he did not believe he had been deceived.
He told the committee his role was merely to "satisfy" himself that Lord Ashcroft would spend enough time in the UK to qualify for his peerage, and that the Conservatives and the authorities agreed on the nature of the undertakings that he was giving.
Sir Hayden stressed that he was not a tax expert and did not, at the time, appreciate the distinction between domicile and non-domicile status.
Tory members of the Public Administration Committee boycotted the hearing.
They have complained to the committee chairman, Labour MP Dr Tony Wright, over what they say is a "partisan" inquiry.