'No more failures'
In a written decision, Miss Aitken said: "These fleets must contract until full compliance is achieved and that means no more prohibitions, no more failures at annual test, no more missed inspections, and meticulous record keeping to the standards indicated by the Guide to Maintaining Roadworthiness."
Miss Aitken said that Mr Duncan, who is also transport manager of both firms, had "lost sight of some fundamentals in recent years".
She wrote: "My curtailments are intended to have an impact on the operator's business and the size of the transport operation.
"This transport operation has to shrink in size and become properly managed."
Miss Aitken added: "This is an atrocious case of an operator well aware of the responsibilities on an operator."
In his submission to the inquiry, Mr Duncan, who has been in the haulage industry since leaving the Army in 1961, said he "did not sacrifice safety for money".
Denny Tipper Transport Ltd's vehicle license will be reduced from 45 to 18 for six months, and Denny Skip Hire Ltd's from 14 vehicles to seven.
The commissioner also gave Mr Duncan the "strongest warning possible" as a transport manager.