Tunnel operator Eurotunnel was criticised for failing to replace open sided lattice framed lorry carriers with enclosed rolling stock.
The tunnel operator was also attacked for failing to install fire suppression systems in the lorry wagons and for failing to provide adequate protection to the tunnel's concrete lining.
The fire broke out at 2.57pm BST last Thursday on a shuttle train in the twin bore crossing's North Tunnel, 11km from the French entrance.
The source of the blaze, which burned for 16 hours, was a lorry reportedly carrying chemicals.
The fire spread to other trucks destroying six carriages and one locomotive. No-one was killed but 700m of the tunnel was damaged.
After the fire the British Fire Brigades Union (FBU) hit out, claiming recommendations it made 12 years ago following the Channel Tunnel fire in November 1996 were ignored.
That fire burned for seven hours and caused £200M of damage to the tunnel.
FBU south east general secretary Jim Parrott said: "We submitted a report after the last major fire 12 years ago, and our main concern was open-sided wagons.
"We wanted closed trucks that would contain any fire. Considering there are 40,000 vehicle fires per year in the UK, it is remarkable there have not been more fires in the Channel Tunnel since," he said. Eurotunnel uses open-sided wagons to transport HGVs through the Channel Tunnel.
"In an open-sided wagon, any fire will be fanned by the speed of the train.
"In a closed wagon, you would take people away from their vehicles, and if a fire is detected, you could then fill a truck with either an inert gas or compressed air foam, both of which are very efficient at putting out fires, and more compact than water-based systems," he said.
A prototype on-board fire suppression system was developed and tested by Eurotunnel over six years after the November 1996 fire. This system involved installing a water tank at one end of the shuttle train with pumps and pipes able to distribute water to the wagons in a fire.
Eurotunnel abandoned the development of the system concluding that it would be unreliable, expensive to maintain, and would deliver few safety benefits.
The official Rail Accident Investigation Branch report into a less serious, fire in August 2006 also cited the lack of suppression.
"The current design of the carrier wagons would not prevent the spread of the fire to involve many HGVs (as was the case in the fire in November 1996).
"A fire of this type could cause major structural damage to the tunnel and disruption of the tunnel's mechanical and electrical systems.
"It is most unlikely that intervention by firefighters would significantly control or limit the damage caused."
"In order to prevent the spread of fire between carrier wagons it would be necessary to adopt containment of the carrier wagons, an on-board fire suppression system, or a combination of the above."
A Eurotunnel spokesman defended the company's approach. "No safety case was made to install covered wagons," he said.
"From the perspective of fire protection and fire safety, it would be harder to get into a covered wagon, and the properties of the cover would negate its purpose," he said.
He also defended the lack of on board fire suppression systems and highlighted the presence of fire detectors.
"There are no onboard sprinklers. There are smoke particle and flame detectors. If a fire is found, then the procedure is we stop the train and move passengers and use the fire and rescue services.
"Sprinkler systems are not considered by all the safety experts to be the adequate solution and are not a significant improvement on what is already there."
Damage to the tunnel is likely to be far worse than in 1996, when the section of damaged tunnel was closed for six months.
Capita Symonds director of civil engineering and tunnels specialist Richard Lunniss said: "The last significant fire burnt for six to seven hours, and there was significant spalling. Half the concrete came away over a significant length."