Ron Gould, the election expert commissioned to find out who or what was responsible for the Scottish parliamentary voting fiasco, was paid in euros although he is a Canadian citizen.

Mr Gould's contractual details emerged yesterday at the Scottish Select Committee's inquiry into the handling of the May 3 election but no explanation why was given as to why he was not paid in sterling or Canadian dollars.

A spokesman for the Electoral Commission said Mr Gould was paid in euros at his own request, and according to the contract he was paid 600 (about £420) a day, plus 100 in expenses.

Mr Gould's report dominated the Commons proceedings as MPs struggled to understand why so many aspects of the elections has gone wrong, including the unprecedented numbers of spoiled papers, the electronic counting process, the postal voting arrangements, the decision to hold Holyrood and council elections on the same day, and the decision to combine both Holyrood votes on the same paper.

The committee agreed to summon Mr Gould to the Commons to give evidence - principally to explain why he felt compelled to write a letter clarifying aspects of his report - but Peter Wardle, the chief executive of the commission, revealed that Mr Gould was keen to co-operate with parliamentary committees.

Sam Younger, the chair of the commission, totally rejected suggestions of "political interference" in the Gould report, which apportioned responsibility for the election debacle in different quarters.

Mr Younger did accept that the commission, which costs the taxpayer £24m a year, had not put voters at the heart of the election process but he rebutted other criticisms.

He told MPs that parliament had given the commission no discretion to interfere on ballot descriptions.

MPs impressed on the commission the inconsistencies throughout the system. A number of MPs including David Hamilton, Midlothian MP, and Ian Davidson, Glasgow West MP, complained that they were not allowed to check doubtful ballot papers.

Mr Younger supported Mr Gould's recommendation of a chief returning officer for Scotland but later MPs suggested such an appointment might be an extravagance.