The 143 page report, commissioned by Network Rail’s board, but conducted independently concluded that “all of the allegations about illicit payments to Mr Coucher (Network Rail’s former chief executive), and the use of offshore accounts, or huge amounts of cash, to make payments under compromise agreements to departing employees were groundless.”

The report also said, “it is hard to avoid the conclusion that the TSSA (Transport and Salaried Staff Association)...introduced a series of increasingly serious allegations of financial impropriety against Mr Coucher for which it had no substantial evidence.”

Twelve allegations of misuse of public funds and serious financial impropriety, presented by the TSSA and present or former employees were investigated. The allegations related either to illicit payments to Iain Coucher and related financial impropriety or the misuse of compromise agreements and the behavious of Peter Bennett (HR director). Of the 12 allegations, 11 were found to be groundless or unfounded. The remaining allegation, about misuse of compromise agreements, had two components. On one of these components the report found no misuse of public funds. On the second, there was no basis for allegations on three out of four cases put forward by the TSSA. However, in the fourth case the report concludes that there was misuse.

Rick Haythornthwaite, Network Rail’s chairman, said: “I am grateful to Antony White for his thorough investigation and report. His conclusions have confirmed earlier internal investigations findings that there was no case to answer regarding financial impropriety.

“However, in concluding that public funds were misused with regard to one compromise agreement, Antony White is essentially expressing disagreement with the conclusions of internal investigations undertaken in 2008. With regard to the implied criticism of the company’s internal governance and levels of transparency, the new Network Rail board has been alive to the issues raised and already taken action to make significant changes. Network Rail is profoundly different today in terms of both its leadership tone and standards of acceptable behaviour.

“The scale of the excoriating campaign waged by the TSSA against the company, and in particular against Iain Coucher regarding these groundless allegations, was unacceptable and has done great damage. I very much hope that those of the Network Rail team who are members of the TSSA reflect on whether this is how they wish their union to represent their best interests and urge it to move to a more collaborative footing.”