The “mindless” hoaxers who left a fake bomb in a Watford pub toilet will be severely punished, police have warned.

Dozens of people were evacuated last Thursday evening after the device was discovered in The Flag, in Station Road, at about 6.10pm.

Countless more commuters were left stranded when police ordered the closure of Watford Junction and cordoned off surrounding streets.

A controlled explosion was later carried out by members of the Army’s Royal Logistics Corp, who feared the device – a mobile phone and collection of wires taped together – posed a genuine threat to public safety.

Later analysis confirmed it to be a malicious hoax designed to look as realistic as possible – but not before valuable police time had been wasted and major disruption caused.

DCI Shirley Sargent condemned an “unbelievably mindless act” and promised to bring those responsible to justice.

No arrests had been made at the time of going to press.

The shocked pub-goer who found the device, meanwhile, described one trip to the loo he will never forget.

Martin Elsen, 41, was enjoying an after-work pint at the pub as he waited for a bus home to Abbots Langley.

He told the Watford Observer: “I had just been to the toilet. I went to wash my hands and saw something on the sink that caught my eye.

“It was a really old style mobile phone – well over ten years old – with a lot of silver coloured, really thick tape around it.

“It was very bizarre. It had some string or cable coming from it that was wrapped around one of the taps. I don’t know if it was stuck on the sink or just resting on it – I didn’t want to touch it to find out.

“Against the phone there was a small book. I can’t remember what it was called but it definitely had a reference to Ireland on it.

“I asked for the manager and the police arrived soon after that.”

Hertfordshire Constabulary confirmed later that it was not investigating any Irish republican or political links to the incident.

Mr Elsen added: “I was a bit shocked – it’s the last thing you expect when you’re having an after work drink.

“I wouldn’t say that I was scared but I was certainly a bit nervous. I just don’t understand why anybody would have left it there. Maybe they thought it was a practical joke.”

DCI Sargent added: “Those responsible have wasted the extremely valuable time of all the services involved and I would like to make it clear that we are committed to tracing those responsible and ensuring they are dealt with in the courts.

“Investigations to establish the reason why this suspicious package was left at this location are ongoing but I would like to reassure people that at this stage we believe the intent of leaving the package was to cause disruption rather than harm.”

Anyone with information should telephone police on 0845 3300 222.

Click here for more stories on the bomb hoax .