So far, it’s true to say, that despite heavy negative coverage for the Conservative Party day after day about Lord Ashcroft, there hasn’t been much sign of damage to the Conservatives in the opinion polls.

In some ways that reflects the degree to which the issue plays to natural political cleavages: is doing everything you can within the law to avoid paying taxes acceptable? Plenty of Conservatives will answer “yes”, so discovering quite what lengths Ashcroft went to – and the fact of him being a Parliamentarian – doesn’t really damage their view of the party.

But there are three reasons to believe this affair will still hurt the Conservatives badly:

1. It has damaged the credibility of David Cameron and William Hague with journalists who now know now incomplete and inaccurate answers they both gave to their questions were. As New Labour found out, treat journalists badly for too long and it comes back to bite you. Moreover, the journalists who are most critical of Ashcroft cut across traditional party lines. The Spectator and The Times (who have just run a story about Ashcroft’s funding of campaigning in 2005 – “The Conservative Party’s last general election campaign was partly financed with a £750,000 loan from an offshore haven”).

2. Negative stories have a habit of building up, not hitting a party’s support – until the dam breaks. Britain tumbling out of the ERM in 1992 was a classic such moment: after that, all sorts of issues which before hadn’t taken support away from the Conservatives were then used by the public as sticks with which to beat them. It’s like a relationship that goes sour; all sorts of things from the past get dragged up. So the Conservatives are skating on very thin ice, with an awful lot of danger building up below.

3. But perhaps most importantly, it’s an issue on which many Liberal Democrats and Labour supporters are of a similar mind: privileged Tories skimp on paying tax, want to cut tax for the very richest and cut services for the rest of us. That’s a powerful motivation to encourage anti-Tory tactical voting to continue at the levels seen in 2005. Not so much a case of tactical unwind as tactical rewind.

And a case where the role of The Times, the newspaper of choice of many floating Conservative/Lib Dem voters and former participant in long-running legal dispute with Ashcroft, is particularly important.

Meanwhile, in the latest twist to the story, The Guardian reports:

Fresh allegations against Lord Ashcroft, this time over his links with a corruption scandal in the Caribbean, are made in high court documents obtained by the Guardian today.

In a hotly disputed libel suit, the Conservative party deputy chairman is accused of providing loans of more than $5m to the disgraced former premier of the Turks and Caicos, Michael Misick, through the local bank Ashcroft controls. According to his opponents, he “ought to have been aware that Mr Misick was corrupt”.

The billionaire Tory donor is also accused in the court pleadings of an “alarming” close relationship with William Hague, who could become the foreign secretary in control of the scandal-hit islands in the event of a Tory election victory. Ashcroft’s relationship with Hague was highlighted this week when it emerged he gave a “clear and unequivocal” assurance that he would become a permanent resident of the UK, but became a “non-dom” for tax purposes.

Hague and other Tories are alleged to have made trips arranged by Ashcroft to the islands, currently placed under direct British rule. Those visiting allegedly included Andrew Mitchell, the shadow international development secretary, Michael Ancram, then in the shadow cabinet, and MP Mark Simmonds.

The allegations are contained in a fighting defence filed by the Independent newspaper, which Ashcroft is suing for libel. Ashcroft complains that two articles contained false statements which have caused him “anger and distress”.