AGGRIEVED private shareholders in Railtrack are to give Alistair Darling, the Transport Secretary, one last chance to consider compensating them before launching the UK’s largest class-action suit.

Andrew Chalklen, chairman of the Railtrack Private Shareholders Action Group, told The Times he would send the shareholders’ particulars of claim to Mr Darling in the next two weeks. If the minister does not make shareholders an offer, legal action against the Government will begin.

The action group has raised a £2 million fighting fund to take action over the decision of Stephen Byers, the former Transport Secretary, to put Railtrack into administration, so depriving shareholders of their property. The fund is double the amount that the company set out to raise after 41,000 former shareholders joined the fighting fund, contributing an average of £55. The entire fund has been raised by private investors, without resort to institutions.

Mr Chalklen would not comment on the sum the group is suing for, and the group is coy on details of its case. However, he said lawyers would study changes in the depreciation policy of Railtrack’s successor, Network Rail, which flattered Railtrack’s 2002 profits by £1.5 billion. That change, if done by Railtrack’s former management, would have shown a £295 million profit in 2002.