John Gibbons, former chief architect of the Scottish Executive, retired last April. He had been on secondment to work as the client for the parliament.
But it has now emerged that he was immediately reappointed as a consultant to provide 'professional and technical expertise' to the parliament, a contract that is estimated to be worth £34,000.
Gibbons is now also contracted to the parliament as part of the Post Completion Advisory Group, in a deal worth £14,000. The group has been established to advise the parliament on the closure stage of the project.
But parliamentary authorities have moved to head off any controversy. 'Dr Gibbons had been working for the parliament but reached retirement age before the work was completed,' a spokeswoman said.
'The parliament has therefore kept him on through a part-time consultancy contract to enable him to continue to advise us on concluding the Holyrood contracts.
'Only Dr Gibbons has the necessary experience and knowledge that we sought,' she added.