Deep under the English Channel welders disappear into clouds of sparks as they repair steel reinforcing bars that were damaged when a truck shuttle caught fire in the Channel tunnel in September.

Slideshow: Fixing the Channel tunnel

Robert Wright assess efforts to repair the fire damage

In little clusters on scaffolding that stretches into the far distance, workers are toiling away at the damaged tunnel walls. Alongside the welders, plumbers install vital pipework and the walls of the tunnel are being blasted with liquid concrete, creating a deafening roar.