Simcock, then National MP for Hamilton West, said in the letter he had not seen his 24-year-old daughter for two years, according to a front-page article in the Waikato Times on December 2, 1997.
He asked to "help make Charlotte and her parents very happy by arranging for her parents to visit London in March next year".
Simcock said the letter was "just a bit of playful fun", the Waikato Times reported.
He had not entered politics in the hope of getting free overseas holidays, but if his nomination for a Commonwealth Parliamentary Association trip had been successful, he would have accepted it, according to the newspaper.
"It was a humorous way of putting my hand up and most of my colleagues saw it that way. It was an error of judgment committing it to paper and I'll just have to live through that," Simcock said to the newspaper.
He was not awarded the trip.
Former ACT MP Rodney Hide, who made the letter public, told the Herald he remembered the incident well.
"The shock at the time was that MPs would turn up and hardly get their feet under the table and be applying for trips and I know that it shocked their National party colleagues, who promptly leaked it to me to embarrass them."
Simcock's role as DHB chair is not the first time he has been in governance positions of organisations that have come under scrutiny.
He was Hamilton mayor when the city hosted the V8s street race and a PwC review of the event found Simcock was involved in keeping financial problems about the V8s from councillors for two years.
The report also criticised his council for having too many meetings behind closed doors.
The council's management team was reported to have spent millions of dollars without authorisation and kept the council in the dark over significant issues.
Ultimately the failed street race cost Hamilton almost $40m.
Simcock was also on the board of Karapiro 2010 Ltd which was the organisation set up to run the 2010 World Rowing Champs.
A Sparc (Sport and Recreation New Zealand) review into the event following a budget blowout was highly critical of the board, saying there was a lack of clarity around its role and responsibilities, and poor financial monitoring.
Simcock said that, while the raising of these matters were part of a orchestrated campaign to smear his reputation, it was actually damaging to the DHB.
"I long ago publicly accepted responsibility for the role I played in the V8 event.
"My role on the Rowing World Championship board was to represent the interests of Hamilton city as one of the host councils, and was so peripheral to the operation of the event that the investigation that followed did not even contact me."
He did not respond to requests for comment on the caucus letter.
Meanwhile Simcock's expenses at Waikato DHB for the past three years, released to the Herald under the Official Information Act, show he spent $35,076.
One trip in the 2014/15 year to a patient-centred primary care collaborative conference in the United States cost $9933.
Two trips to HealthTap, the company that powers the DHB's SmartHealth app, in November 2014 and April 2016 cost $1604 and $7181 respectively. The reason for travel was given as "due diligence".
During both of the visits Simcock took personal trips to New York, where it's understood his daughter now lives.
However a travel request form for the 2016 visit - signed off by then audit committee chairwoman Gay Shirley - shows Simcock was to reimburse the flights between San Diego, Atlanta and New York.
He paid the $274 for the internal flights a month after the trip.
There was no travel request form for the 2014 visit because Simcock was already in the US when the invitation to go to HealthTap came through, and none was filled out retrospectively.
Board member Dave Macpherson, former Labour MP Sue Moroney and Association of Salaried Medical Specialists executive director Ian Powell have all called for Simcock to stand down as chair.
Moroney said she was concerned about the letter Simcock wrote to caucus.
"I hope that Bob Simcock didn't take that sense of entitlement into his current role as the Waikato DHB chair because the CEO he appointed, Nigel Murray, clearly did have that same sense of entitlement."
Macpherson said he had no confidence in Simcock following the Audit NZ report which showed poor processes around management of Murray's expenses.
