Bill Crothers's element-time position had be2en "agreed" to with the aid of the cupboard workplace, the workplace of the Advisory Committee on commercial enterprise Appointments delivered.
Its chairman Lord Pickles complained of a "loss of transparency" over the scenario.
but Mr Crothers said he were taken on with the aid of Greensill in a "obvious" manner.
Labour referred to as his twin employment "superb and stunning".
The disclosure approximately Mr Crothers - who have been the government's leader procurement officer previous to being taken on with the aid of Greensill - is the trendy of several tales concerning the now-collapsed financial firm.
It hired former prime minister David Cameron as an adviser from 2018.
The economic instances and the Sunday times found out that Mr Cameron had contacted numerous ministers, inclusive of Chancellor Rishi Sunak, to push for greater involvement in government loans schemes for the organization.
Boris Johnson has installation an inquiry into lobbying - tries to persuade governments to alternate coverage - which include Greensill's function.
authorities assets stated this would also now have a look at the state of affairs surrounding Mr Crothers.
Mr Crothers, who had already left his process as leader procurement officer but remained a Civil provider employee, joined Greensill as an adviser to its board in September 2015.
The letter from Conservative peer Lord Pickles to leading civil servant Alex Chisholm says: "This become agreed by means of the cupboard workplace below its internal conflicts-of-hobby policy."
Lord Pickles asks for "steering on the conflicts-of-hobby procedure" undertaken.
The letter adds: "the shortage of transparency round this element-time employment with Greensill may additionally have left the deceptive influence that Mr Crothers had wilfully disregarded the responsibility to seek advice."
Mr Crothers left the Civil carrier in November 2015, two months after taking on his position at Greensill. He have become a director of the company in late 2016.
A letter from Mr Crothers to Lord Pickles, a former Conservative celebration chairman, written in advance this week, has additionally been published.
In it, he says: "i'm concerned that there can be a view that I did no longer observe proper method concerning my role with Greensill Capital.
"I assure you that I completely respect the required process and your workplace, took steps to comply, and believe that I did so."
He adds: "i used to be obvious approximately the flow to Greensill Capital, and it became widely known at the time."
The shadow cupboard office minister Rachel Reeves said: "that is an great and shocking revelation.
"The Conservatives have weakened the rules a lot they may as properly rip them up and begin once more."
The authorities inquiry in to lobbying is expected to record via the quit of June, however Labour says it does not go a ways sufficient.
it's going to use an opposition day debate on Wednesday to pressure a vote on whether or not to establish a brand new Commons select committee to analyze the difficulty.
in contrast to ordinary opposition day votes which are symbolic, this one might be binding if it passes due to the fact Parliament would be figuring out if it should do some thing.
A cupboard workplace spokesperson said there would be a reaction to Mr Pickles's letter "in due route".
They delivered that the "review into Greensill Capital and deliver-chain finance" would be "wide-ranging".
Mr Cameron has stated he did now not damage any codes of behavior or regulations on lobbying and that he welcomes the investigation released through Mr Johnson.