THE Glasgow City Council whistleblower who claims he was ordered to fix the outcome of the George Square redesign contest for Labour leader Gordon Matheson has submitted fresh evidence to Scotland's ethics watchdog.

Kerr Robertson, the council's former lead architect, met with the Public Standards Commissioner last week, and handed over a dossier containing a detailed account of his part in the process. It is understood he also included a series of emails involving other council officials.

The international competition to give George Square a £15 million overhaul ended in farce earlier this year when Matheson announced the scheme had been axed within minutes of the judges choosing a design he disliked. His preferred option came fourth, leading to claims from council insiders he had "thrown his toys out the pram".

The abortive exercise cost taxpayers £100,000 and the architects involved another £200,000.

Matheson is now being investigated by Police Scotland's Major Crimes and Public Protection Division, and watchdog bodies.

The Sunday Herald revealed last month that the Royal Incorporation of Architects in Scotland (RIAS), which ran the competition, had lodged a complaint with the standards commissioner alleging Matheson repeatedly violated the Councillors' Code of Conduct.

Matheson faces claims of interfering in a legally-binding procurement process, improper bias, attempted staff coercion and trying to steer the contest towards his favoured design. If proven, the watchdog could suspend Matheson.

However, the Labour boss denies any wrongdoing and says he is confident of being cleared.

The RIAS complaint included a statement from Robertson, who recently retired as lead council architect and projects director.

Robertson claimed that, despite the contest being bound by EU procurement law, he was told six weeks before the final judging began that Matheson would "choose the winning design" and Robertson's job was "to ensure the other jury members would fall into line".

The fiasco is also being looked at by Audit Scotland and the council's internal audit unit.

Graeme Hendry, leader of the SNP opposition on the council, said: "A fresh dossier of evidence will not be a surprise to most, but it is a fresh blow to [Matheson's] credibility."

Conservative councillor David Meikle said: "This is another nail in Cllr Matheson's political coffin."

The standards commissioner does not comment on ongoing investigations.

A council spokesman said: "Cllr Matheson did not at any time seek to improperly influence this process. There was no public appetite for a radical redesign."