The same day Twyford received Genter's letter he received advice on whether the phasing of projects allowed public transport, walking and cycling ones to happen first.
The following week he received advice on the potential downsides of delaying or removing a second Mt Victoria tunnel.
The existence of the letter was only revealed through an Official Information Act request response.
It raised the eyebrows of local National Party MPs considering both Twyford and Genter's responses to written parliamentary questions suggested there was no correspondence between them over LGWM.
During Question Time today National's Transport spokesman Chris Bishop asked Genter if the reason she didn't disclose the existence of the letter when first asked was because she was embarrassed by its contents.
Genter rejected that and said it was a mistake. As soon as the oversight was realised, the answers were corrected, she said.
Asked whether she would ever release the letter Genter said she could "assure all members that the Government has nothing to hide" and that it was withheld in line with the OIA.
She again referenced reasons including to maintain the effective conduct of public affairs through the free and frank expression of opinions between Ministers of the Crown.
Bishop did clear up one thing, the letter did not refer to "car fascists".
The day LGWM was announced Genter joined discussions on Twitter posting the comment "we need a few car fascists to stop opposing infrastructure that gives more people the option to walk, cycle or scoot safely if they wish."
Genter later acknowledged that wasn't her best choice of words.