A 19-year-old who admitted drug driving twice in little over a month has been banned from the roads for 18 months.

Owen Lee, of Links Avenue in Cromer, was stopped by police on March 18 on his home street, while he was under investigation for a previous drug drive offence on February 11.

During the earlier offence he had been seen by police in Marsham at 2.45am and failed a roadside saliva swab, prosecutor Victoria Bastock told Norwich Magistrates Court on Tuesday.

Blood tests came back positive for cannabis and ketamine, but had not been returned by the time officers saw Lee's car being 'driven erratically' on Links Avenue five weeks later.

'They noticed his pupils were wider than normal and he informed officers he had smoked a spliff earlier that evening,' said Ms Bastock.

'Officers also found a coffee jar containing 12.61 grams of cannabis in the car. Blood samples were taken, showing he was over the legal limit. He told officers he thought his driving was fine.'

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Ian Fisher, mitigating for Lee, told the court he had not fully understood he might be charged for drug driving after being released from custody in February.

He added Lee had been 'a fraction' over the limit on each occasion.

'If somebody gets a positive drug swipe they give them a blood test and release them under investigation,' he said. 'At some time the results come back.

'It is clear he had a clouded notion of what released under investigation added up to. He knew for sure he hadn't been charged with anything. Of course the risk was he was going to end up being charged.

'These are not cases where it is said he was unfit to drive through drugs. It is a case where he was driving with drugs in his blood stream.

'He has held his driving licence for about one year and he has never been in any kind of trouble before.'

Chair of the bench Jean Bonnick told Lee: 'You know you shouldn't drive when you have been taking drugs. You would have been told that the first time police stopped you. Hopefully they told you cannabis stays in your system at least three days.

'Your employers may take a dim view of this. If you take drugs recreationally at the weekend it is still there on Monday.

'Think on before you take ketamine or cannabis in the future.'

Lee was banned from driving for 18 months for the March offence, and 12 months for the February offence, to run concurrently.

He was also fined a total of £735.