Lord Hardie, chair of the inquiry, conducted proceedings at Waverley Gate for the inquiry’s first hearing before a public audience.

Lord Hardie announced the seven parties - including City of Edinburgh Council and the Scottish Government cabinet - which have been designated as “Core Participants” in the inquiry.

City of Edinburgh Council has already set aside £2 million to cover the cost of co-operating fully with the inquiry.

Lord Hardie also gave a brief summary of the work undertaken by the inquiry since it became fully operational in June 2014.

Organisations involved in the inquiry initially provided access to as many as 500 million pieces of potential written evidence, but the inquiry eventually determined that only six million would be relevant to its work.

This evidence is now being filtered by a document management system.

The trams began operating at the end of May last year after six years of disruption and a long-running dispute between the council and contractors.

The eventual cost of £776 million was more than double the sum earmarked for the project.

The inquiry is looking at the project, examining its governance, management and other areas to try to find out why it was delayed, and why it “cost considerably more than originally budgeted for and delivered significantly less than was projected through reductions in scope”, according to its remit.