The discovery sheds new light on a breakdown in the relationship between governors and senior teachers at the school which resulted in the governing body resigning.
He also commissioned Richmond construction company, Randall Orchard, to draw up designs, later telling governors the company was his preferred choice.
However, governors and North Yorkshire County Council stepped in after it emerged both decisions were taken without the governing body’s involvement or approval, and without the arrangements conforming to public procurement policies.
Governors voted instead to pay the companies for the work they had already done and start again with a tendering exercise that met procurement guidelines.
Documents obtained by The Northern Echo reveal that governors were also not asked before the school’s contribution towards the pavilion project rose from £150,000 to £250,000.
In a further revelation, it emerged the governing body had a discussion in January of this year about how to tackle a £350,000 budget deficit predicted by the school for 2014/15 and 2015/16.
It has already emerged that the former governing body resigned enmasse after a breakdown in relationship with the school's senior leadership.
An interim executive board (IEB) has been appointed to run the school.
Anne Skeoch, former chair of the governing body which resigned, declined to comment on the new information.
Graeme Newton, Randall Orchard managing director, said the company was approached by the school to provide budget and planning advice as it was aware the company had previously completed similar schemes for Barnard Castle School, Reeth and District Athletic Club and Richmondshire Rugby club.
North Yorkshire County Council said itself and the IEB had been made aware of these matters and they would be considered in due course.
Chris Lewis, chair of the IEB said the board's priorities included adopting policies and procedures as a foundation for establishing good governance.
He added: “The IEB will put the students first, focus upon the proper stewardship of the school since the board's inception and work tirelessly to secure its future success.
"It is apparent that Richmond School is a good school. Its trajectory is towards becoming an outstanding school.”