He said that while he left the firm in March/April of 1987, and Mr Shirtcliff was still there, he was sacked soon after, though "not for reasons of technical incompetence".
The issues he had with Mr Shirtcliff were in his defined role of acting as a go-between him as managing director and the site foreman, Bill Jones.
"We had a team who, essentially, didn't need supervising, but what they did need, from time to time, was guidance and supervision," Mr Brooks said.
He accepted that without that, it could become a "potential factor" in construction issues of the ill-fated office block.
Mr Brooks didn't know if Mr Shirtcliff visited the building site every day, but "he certainly should've been".
Counsel assisting the commission Mark Zarifeh said Mr Shirtcliff claimed in his brief of evidence that his involvement with CTV was "limited".
Mr Brooks also revealed that the CTV building was designed to maximise office rental space for as cheap as possible.
He said it was to cost $2.45 million.
Mr Brooks had worked with Mr Blair, and his company Prime West Ltd, on other jobs in Christchurch during a construction boom in the 1980s.
He drew up a rough floor plan "on a piece of paper" which showed a lift shaft at back of building at a Prime West-owned piece of land at 249 Madras Street to "allow maximise rental space".
Mr Brooks gave the sketch to architect Alun Wilkie to come up with the final plans.
The architect had worked with Prime West on other jobs and Mr Brooks said they knew to come up with final plans that made it "as efficient as possible to maximise rental space".
The contract to do the structural design was given to Alan Reay Consultants.
Williams Construction estimated a contract price of $2.45m, which would give the firm a profit of around $300,000.
The commission was told that by the time the building had been completed Prime West hit financial troubles. It later went into receivership.
Early in 1987, Mr Brooks, development manager Tony Scott, and Mr Shirtcliff incorporated a new company, Union Construction Ltd and they all resigned from Williams Construction.
The CTV contract was then signed over from Williams to the new company.
Mr Brooks accepted, under questioning from Mr Zarifeh that progress on the CTV building slowed.
However, he denied that it affected the quality of workmanship.
The hearing continues.