The shock of seeing the bill led the government of Yves Leterme to commission the audit. According to reports at the time, the government was hopeful of being able to reclaim some of what appeared to be inflated costs from the contractors and sub-contractors who had taken part in the project. To give one example: the doors at the rear of the building which are intended to be used by prison transports to bring prisoners to court were found to be too low for the standard size of van used by the prison service. They had to be ripped out and rebuilt.

But the auditors, in a report leaked last week to De Tijd newspaper, have bad news for the government: the lion's share of the responsibility for the cost fiasco lies in its own backyard, specifically at the Regie der Gebouwen, the government agency which, under the auspices of the finance ministry of Didier Reynders, operates and manages the government's real estate. It was the Regie that was blamed two weeks ago for dragging its feet on improving security at prisons, leading to the recent helicopter jailbreak in Bruges.

The Regie did not intervene on the many occasions when costs went over budget, the report said. As a result, contractors can no longer be held responsible. "The Regie is the party who gave the green light, who took the final decisions, and who has the ultimate responsibility," the report says.

According to the Regie, the problem was not so much an overspend, as an underestimate of likely costs at the outset. The initial budget was "unrealistic," the agency said in a statement. They also gave a list of the factors that were still unknown at the time the budget forecast was drawn up: location, cost of building land, architect and cost of financing. "This is what laid the foundations for a fundamental lack of clarity during the design and implementation of the project," the statement reads.

That "lack of clarity" was characteristic of the whole project. The justice ministry told the Regie how many courtrooms it required, but little else. While the project was underway the number of cells doubled from 50 to 100. Nobody had foreseen the presence of female guards, who would need separate showers and toilets. The width of all exits was extended on orders from the fire service. Finally, star architect Richard Rogers demanded a fee of 7% of the building cost, higher than the standard 5%. He also submitted exorbitant travel and hotel expenses. It is estimated he walked away from the project with €26 million.

For now, the Regie is stressing that the full report of the auditor has not yet been released. When it is, the Regie will study its conclusions and "take the necessary steps".