Mike Lynch, the founder and erstwhile CEO of the British software house Autonomy is not a man given to hiding his light under a bushel. Indeed, he's a chap with a reputation for an uncertain temper and a penchant for calling a spade a bloody great big steel shovel with which one may belabour a bad-tempered badger, were one so inclined. However, over recent months Mr. Lynch has been uncharacteristically quiet in the ongoing spat between him and HP about exactly who did (or didn't) do what to whom during the time the US company was acquiring Autonomy back in 2011.

However, it turns out that Mr. Lynch has simply been keeping his head down and his powder dry. This week, on the very day of HP's annual investor meeting on Wednesday in Santa Clara in Silicon Valley, Mike Lynch popped up over the parapet and propelled his primed pineapple at the HP trenches.

He published an open letter on the Internet claiming that HP has been systematically "misleading" both the market and its shareholders in regard to the real reasons it was forced to write-down US$8.8 billion of its $11.1 billion purchase price for his company.

Fortunately, Leo Apotheker, whose term as CEO of HP was as disastrous as it was short-lived, didn't last long after the HP board rumbled that his master plan for Bill and Dave's lovingly-created computer and comms hardware powerhouse was to turn it into just one more "me too" American software company. However, he did manage to push through the Autonomy acquisition before being shown the door - and that problematic purchase is the cause of the ongoing attrition.

A year and more after the purchase, Apotheker's replacement as CEO, Meg Whitman, dropped a bombshell of her own and wrote down close to 75 per cent of the value of the Autonomy acquisition - apparently after investigating allegations by an anonymous whistleblower that Autonomy's records and accounts were riddled with "accounting improprieties, disclosure failures, and outright misrepresentations."

HP has always maintained that it was completely unaware of any dodgy dealings and/or excessively creative accounting on the part of the British company but the denial didn't stop HP shareholders from issuing a class action law suit against HP alleging that it did indeed know about various irregularities but continued with the buy-out anyway. Meanwhile in England, in May last year, the Serious Fraud Office launched a separate (and ongoing) investigation into Autonomy.

Then everything settled into an uneasy silence that was rudely broken this week. In his open letter, Mike Lynch writes that "HP has not provided information or evidence to the Autonomy team to substantiate any allegation. Instead, it has selectively leaked documents and information to the international media, frequently using material taken out of context to create false impressions and smear our reputations. Since the last HP shareholder meeting, reports in the media have demonstrated that HP has documents in its possession that show beyond doubt that statements it made on November 20 (that's November 2012, Ed.) were misleading. Further, these reports have shown that senior people at HP knew these statements were misleading long before they were made."

Lynch's querulous missive also lists a series of questions that HP "needs to answer". These include the provision of an explanation of why HP has to failed to tell Autonomy executives the details of the allegations they face, just how, when and where Autonomy's account's failed to spot and address a series of what HP refers to as "missed" items, how HP calculated the $8.8 billion write-down and why it will not release those details to Autonomy, together with an explanation of what HP knew before the emergence of the whistleblower claims that, allegedly, started the whole debacle.

HP's response has been as terse as it is considered: "As HP has previously reported, it uncovered numerous accounting irregularities at Autonomy prior to its acquisition by HP. HP reported those irregularities to appropriate civil and criminal regulators in the US and UK.HP continues to cooperate in ongoing investigations by those regulators."

As they say in the best tabloids - this one will run and run.