TRAINS across the London Underground are set to grind to a halt after rail union RMT announced yesterday that drivers had backed strike action over a controversial sacking.

Northern Line driver Alex McGuigan was dismissed after a routine breathalyser test produced a positive result but union reps maintain his innocence, suggesting the excess of acetone caused by his diabetes could have produced a false result.

The union called a Northern Line walkout in early December but now drivers have voted by 299 to 221 to shut the entire network down. Dates will be announced shortly.

RMT London organiser John Leach said that the union supported the use of breathalysers among staff — they are barred from drinking from eight hours before they clock on and limited to seven units in the preceding period.

“We are actually asking for further testing when a hand-held breathalyser gives a positive result,” he said.

“The current system is unfair because it doesn’t offer safeguards to those with disabilities or who are on certain diets.”

London Underground has reportedly refused a request from RMT to reinstate Mr McGuigan if an employment tribunal should deem his dismissal unfair.

A post on the Aslef Shrugged blog written by a Central Line driver said this raised questions for management. “The implication is that there’s something they’re not telling us and sadly they have form,” the driver argued.

But Tube operations director Nigel Holness wouldn’t budge, calling on the union to “see sense and recognise that there is simply no point in taking any further action.”

The union said it remained open to negotiations.