Carillion's board presided over a "rotten corporate culture" and was both "responsible and culpable" for its catastrophic demise, concluded a report from two influential parliamentary select committees that was published today.
Furthermore, MPs highlighted "terrible failures" in regulation and calls on the government to carry out an "ambitious and wide-ranging set of reforms" to corporate accountability.
On the former Carillion board, it says careful consideration should be given to whether they breached their duties under the Companies Act and whether they should be disqualified from ever serving as directors.
Carillion had around 43,000 employees, including 19,000 in the UK.
What are the directors accused of?They are guilty of failing to tackle the crisis at Carillion, failing to insist the company paint a true picture of its crippling financial problems.
The inquiry laid into the directors for presenting themselves as "self-pitying victims of a maelstrom of coincidental and unforeseeable mishaps" when they appeared before parliament. Former finance director Richard Adam - described in the report as "the architect" of the firm's highly aggressive accounting policies - says he disputes various quotes attributed to him.
What are the auditors accused of?
The 100-page report also took aim at the big four audit firms, after they "waved through" the indebted construction firm's accounts.
The report was also critical of Deloitte, which it said had failed in its risk management and financial controls role despite being paid £10m, and EY, which provided failed turnaround advice while being paid £10.8m.
Big Four giants Deloitte, PwC, EY and KPMG face extinction if they fail to learn the lessons from the failure of contracting giant Carillion, the head of Britain's leading accountancy institution warned this morning.
"The Competition and Markets Authority must now look at the break-up of the Big Four accountancy firms to help increase competition and deal with conflicts of interest".
But a KPMG spokesman said it believed it had conducted its audits of Carillion "appropriately", and Ernst & Young said it was "extremely disappointed that despite all efforts the business was not rescued".
"Our priority has been to keep public services running safely across the country while saving thousands of jobs", said PwC chairman and senior partner Kevin Ellis. "Because if we don't fix this I don't think we're going to have a profession in 20 years time".
Very few of those involved in the scandal escape censure, from the highly paid and "delusional" directors to the even more highly paid "cosy club" of auditors, the timid and ineffective regulators - and the government.
However, the MPs also concluded that successive governments have nurtured a business environment and pursued a model of service delivery that made a collapse like Carillion's "almost inevitable", while it has also criticised the Crown Representative system - which assigns civil servants to monitor companies in order to provide updates on their performance - as "semi-professional and part-time" and called for an immediate review.
The document said: "When swathes of public services are affected, close monitoring of exposure to risks would seem essential".
Frank Field, who chairs the work and pension committee, said: "Same old story". "British industry is too important to be left in the hands of the likes of the shysters at the top of Carillion".
"That's why we have recently announced a number of measures to support Government suppliers - strengthening our commitment to prompt payment; protecting staff, businesses and small suppliers from irresponsible directors".
'We welcome the report from the joint select committee and will respond fully in due course'.