In today's Australian:
His decision to fake the email followed a conversation with the Treasurer's chief-of-staff, Chris Barrett, on June 4, in which Mr Barrett asked Mr Grech if he had ever received an email from Mr Charlton.
Mr Barrett's question was in response to evidence Mr Grech had given earlier that day at a Senate estimates hearing about the matter.
Mr Grech told Mr Barrett he believed an email existed.
But, unable to find the email on his Treasury email system, he fabricated the communication -- a record of which has never been found despite exhaustive searches -- based on what he said was his recollection.
"It is at this point that I made an error of judgment," Mr Grech told The Australian.
"Rather than preparing a note for file recording the discussion I had with Barrett, including setting out what I thought the exchange as an email that set out what I recollected the original email contained.
"Although the email was not an original, I thought that it would help having a record in the form that it appeared if or when the original could be located."
Mr Grech said that after four months the exact wording of the email might not have been "spot on".
"(But) I was confident that the sentiment of the exchange was accurate -- a position that I still believe today," he said.
Mr Grech then sent the email from his Treasury email account to his private address on June 5, two weeks before his next appearance in the Senate and one week before his meeting with Mr Turnbull.
Mr Grech's meeting with Mr Turnbull occurred in the Liberal leader's wife's office about 3pm and went for about an hour and a half, Mr Grech said.
Ms Turnbull was not present and it is understood she has never met Mr Grech.
Mr Grech said the three men passed around the "email", a single copy of which had been printed out by Mr Grech.
But the Treasury official said he took the copy of the document back and had never provided it anyone. He is adamant that he never gave permission for the email to be used by anybody...
Also, get a look at last night's Australian Story.
It's a fast-moving stunner!
"Things were looking up for Mr Turnbull until he targeted Kevin Rudd with the now infamous fake email in the Utegate Affair.
Australian Story was filming behind the scenes with Mr Turnbull's inner circle as the scale of the Utegate debacle became apparent."