A SHAMBOLIC descent into chaos that left thousands of passengers facing Christmas railway misery was laid bare yesterday in a blow-by-blow report revealing contractors’ failure as the cause.

Unions demanded the return of engineering work to public hands following the findings of a Network Rail (NR) probe.

Signal replacement into London Paddington could not be passed as safe due to errors and discrepancies by subcontractors carrying out the work.

At London King’s Cross repair work ground to a halt because poorly trained operators had struggled to use broken equipment.

Projects that should have been scheduled over several days were squeezed into a shorter time and overrunning work meant lines could not be reopened during the miserable weekend of December 27-29.

Rail union RMT general secretary Mick Cash said the answer was to “bring all works in-house under a single command and control structure” to tackle a backlog of works.

“More than two decades of privatisation, fragmentation and underinvestment has left Britain’s railways with a backlog of maintenance and renewals work that is simply impossible to shoehorn in during the limited window,” he said.

The report for publicly owned infrastructure firm NR shows that the Paddington works unravelled when a safety sign-off on signal replacement by contractor SSL overran by eight hours because of testing work that needed to be “redone or rechecked” and “inconsistencies in paperwork.”

At King’s Cross untested lifting equipment used did not fit correctly and leaked hydraulic fluid.

By the time the old tracks had been cut and cleared by profiteers there was a shortage of freight drivers, leaving engineering trains at a standstill.