Cat now firmly out of bag -

although that City AM article link is still returning a firm "access denied" - but never mind, you can go read, in the G, about  how "Accountancy firms 'use knowledge of Treasury to help rich avoid tax' – MPs" and how this "Experts offering advice on legislation they helped to create is 'ridiculous conflict of interest', says select committee chair" .. 

Margaret Hodge, the PAC's chair, said the actions of the accountancy firms were tantamount to a scam and represented a "ridiculous conflict of interest" which must be stopped. "The large accountancy firms are in a powerful position in the tax world and have an unhealthily cosy relationship with government," she said, calling for the Treasury to stop accepting* their staff to draw up new tax laws.

* presumably she also wants the Treasury to stop placing advertisements inviting said firms (oh and others who feel they can spare the staff concerned and wish to fulfill some public service obligation) to encourage their staff to nominate themselves for seconding to the Treasury, in fact we can probably take that as read.  

Only kidding ! Despite that "which must be stopped" they don't actually go as far as making one of their recommendations "It must stop".  However, as explained in the Report's Recommendation 3 they do want the Treasury to ensure that 

the code of conduct we have proposed for tax advisors sets out how conflicts of interest should be managed when a firm advises government on the formulation of tax law and subsequently provides tax advice to clients in related areas.

For those of you who are particularly keen to see what the PAC thinks, and what other recommendations it has made in detail 44st Report - Tax avoidance: the role of large accountancy firms

or PDF version 44st Report - Tax avoidance: the role of large accountancy firms ()

-----------------------------------------
Update : According to the Beeb no less It is a recommendation in the report ...

Ban 'insider' tax accountants - MPs

A ban on external accountants working inside government, to stop them telling clients about tax loopholes they have found, has been urged by MPs.

The recommendation is in a report on tax avoidance by the Commons Public Accounts Committee.

However, in its report  Tax avoidance: HMRC ‘too cosy’ with accountancy giants the Indie says that 

 "There is a conflict of interest because the top firms of accountants use inside knowledge gained from seconding employees to the Treasury to “sell clients advice” on how to pay less tax, warns Margaret Hodge" and later quote her as saying "“They second staff to the Treasury to advise on formulating tax legislation. When those staff return to their firms, they have the very inside knowledge and insight to be able to identify loopholes in the new legislation and advise their clients on how to take advantage of them. The poacher, turned gamekeeper for a time, returns to poaching. This is a ridiculous conflict of interest which should be banned in a code of conduct for tax advisers.”

Which, I suggest, is not the same as having published a recommendation saying the practice whereby HM Treasury takes staff on secondment from the Big 4 or any other accountancy firm should be banned.   But there you go ... 
--------------------------------------------
Update Update : The G have just (11:40 am) placed an updated piece on line Margaret Hodge urges accountancy code of practice over role in tax laws in which they quote from Ms Hodge's interview on the BBC Today programme :

Speaking on BBC Radio 4's Today programme on Friday, Hodge called for the introduction of a tax-planning code of practice to ensure that accountancy firms brought in by the government to "transfer intelligence and innovation" did not use their position to their clients' advantage.
"Tax reliefs are one of the great areas where the accountancy firms and the lawyers and the companies themselves do take advantage of these perfectly legitimate intentions of government and use them to avoid tax, and I just think it's not on," she said.  "There's a perfectly simple way around this. There should be a code of practice whereby the accountancy firms who do come in and give that technical advice … can't then go off and flog the schemes."

The G also preface that quote with "The large accountancy firms are in a powerful position in the tax world and have an unhealthily cosy relationship with government," she said, calling for the Treasury to stop accepting their staff to draw up new tax laws.

So, according to Ms Hodge herself, she is suggesting that H M Treasury should stop taking staff on secondment from the large accountancy firms to draw up new tax laws but, not having made that a specific recommendation in the report, and perhaps also assuming that the secondments are going to continue - as indeed Treasury Minister David Gauke implied when he was interviewed by the Beeb this morning** - has recommended the perfectly simple solution of "a code of practice, etc. etc." 

**  as had previously been strongly implied by "an Spokesperson", as the G reports

An HMRC spokesman said: "HMRC gives careful consideration to the potential risks, as well as how to mitigate any potential conflicts of interest, before any such secondments are agreed. On balance, the carefully targeted use of secondees is beneficial for the development of tax policy and improving the effectiveness of the tax system."

We can only conclude that the mystery of the recommendation that wasn't made, and why it wasn't, and the fall out from that, is obviously going to run and run...