The hastily arranged visit had been thrown together by Eurotunnel in the hope of pre-empting bad publicity after a pirate video of the tremendous damage caused by the fire was shown on French television.
Even eight kilometres from the seat of the blaze, the smell of soot and smoke was already so strong that most of us put on the face masks provided by the company.
Nothing could have prepared us for the sight when the central security tunnel's diesel bus stopped at the site of the fire. The huge metal tunnel access doors - over a foot thick and virtually undamaged by the fire - had been left open and the entrance was festooned with what looked like fake snow.
Inside the tunnel itself the footpath, the tiny platform running the length of the link, was hung with the same stringy fragments. What looked like decoration in Santa's grotto was actually fibre glass which had been used to protect cable held on a little metal tray. The cable and the tray had completely disappeared leaving behind what looked like scraps of cotton wool.
For as far as the eye can see, 300 metres or more, the concrete of the roof and sides had exploded into popcorn-sized granules, blasted apart by expanding water vapour in the concrete as the heat from the fire became intense. Dust and tiny pebbles covered everything.
The floor of the tunnel was also littered with countless packets of sliced cheese, all still in their little cellophane packets seemingly unaffected by the blaze. They had been part of the cargo of one of the wagons that was nearest the seat of the fire and amazingly had survived the estimated 800-1,000 degree centigrade temperatures.
We were told that one of the neighbouring wagons had been carrying pineapples and the fruit, too, had largely survived intact though charred.
The catenary, the wire which provided power to the trains, has been removed for 600 yards and the damaged section is a jumble of twisted chunks of copper wire and other bits of cable, though the huge cooling pipe and the water pipe used to extinguish fires are both undamaged.
Amazingly, barely a dozen metres of the track bent in the blaze. The fire seems to have concentrated upwards and along the tunnel leaving much of the lower part unscathed. The remains of the most damaged six wagons which were still in the tunnel had been covered with enormous blue tarpaulins on the orders of the Juge d'Instruction (examining magistrate) who is still considering whether the incident was criminal - i.e. caused by sabotage - or not.
When we were allowed a peep into the wagons, they were still recognisable but the roofs had bent in as if a large heavy object had fallen on them, but probably caused by the catenary wire falling down.
Pierre Matheron, the former director of works for the builders TransManche Link who has been brought in to help draw up the repair scheme, explained that 300 metres of tunnel had been severely damaged, 200 metres slightly affected and the worst 30 metres had been virtually destroyed, losing half the 40-centimetre thickness of the concrete.
Mr Matheron said: "This is a very dry part of the tunnel cut through blue chalk and certainly there was never any question of water getting in." However, the question of how to repair this most damaged section remains open and will ensure that it will take weeks and possibly months to bring that tunnel back into service.
Our little party had disturbed the 15 or 20 workers struggling to clean up the damage. They are working in shifts through the night.
There are surprisingly few of them because there is very little space for them to work in and they are in specialist teams concentrating on specific aspects of the task ahead.
Given the sooty and close conditions they cannot be looking forward to the months ahead.Reuse content