After checking their bag, the negotiator re-traced their steps back to the station and arrived to see the now-empty train pulling away.
Nothing was handed to lost-and-found and, back at the office, a privacy incident notification form was completed.
That set off an email chain. One official advised phoning the iwi to fess up and deliver an apology covering points including that the lost document "contains information about quantum, negotiations etc".
In case of media interest a statement would be given acknowledging the breach shouldn't have happened and making clear the employee at fault had been spoken to.
Phone calls were made. Early that May 18, 2016 evening the Office of Treaty Settlements deputy director emailed an update on how the bad news had been received in one instance - philosophically, as it turns out.
"Their response was, 'shit happens'," the ministry official wrote. "They are okay."
Another call was made to the chairman of the iwi who said he understood the circumstances.
The ministry wouldn't release the name of the iwi or negotiators on privacy grounds, and efforts to confirm those involved have been unsuccessful.
According to the Office of Treaty Settlements, there were 35 milestones reached with claimant groups in the 12 months to June 30, 2016, and 23 milestones in the nine months to March last year.
The Herald on Sunday learnt of the incident after asking government organisations to detail cases since 2016 when material had been mistakenly left unaccompanied in public.
Twenty organisations have confirmed over 75 incidents. Those of note include the Tertiary Education Minister having to rush out a report after a Ministry of Education staffer lost a draft version in August 2016.
The draft was later found in a car belonging to a family member of the staffer.
