The England rugby player Danny Cipriani has been convicted of drink-driving after getting behind the wheel having spent the night drinking cocktails and champagne.

The 28-year-old was so drunk his eyes were “glazed”, he slurred his words and could not stand straight after he crashed his black Mercedes into a taxi in London at 5.15am on 1 June last year, Westminster magistrates court heard.

The fly-half, then with Sale Sharks, was breathalysed after the crash in Imperial Road, Fulham, and found to have 67 micrograms of alcohol in 100ml of breath – twice the drink-drive limit.

He was found guilty on Friday after a trial. Cipriani, who now plays for Wasps and earns £3,200 a week, was fined £4,500 and ordered to pay £3,120 in costs. He was also banned from driving for 18 months.

Cipriani claimed he was shocked that the breathalyser returned a positive result, despite admitting he had drunk two espresso martinis and a glass of champagne less than an hour earlier.

His case has been long and protracted after his lawyer, Philip Lucas, tried to get it dismissed, arguing there was not sufficient evidence that the test in the police station was working properly.

The chief magistrate Howard Riddle ruled that there was a case to answer and found the charge proved. “I am satisfied so that I am sure that the breathalyser test machine was working properly, gave a correct reading, and on that basis the verdict is guilty,” he said.

Cipriani’s solicitors announced that he would appeal against the judgment.

Jeanette Miller, of Geoffrey Miller solicitors, said: “I can confirm our intention to lodge an immediate appeal against the verdict delivered in today’s trial.

“Mr Cipriani maintains his innocence and has always disputed being the cause of an accident which led to proceedings against him, as well as the allegation that he was over the legal drink-drive limit – either at the time of alleged driving, or on his arrival at the station, or at the time of the breath test – an assertion supported by the evidence of three forensic experts.

“The case has been riddled with inconsistencies, failings to disclose evidence and decisions made on evidence that, in our view, were insufficient to secure a conviction. We will now seek an urgent appeal and are confident that justice will be done.”

Riddle said: “There is ample evidence from independent witnesses that Mr Cipriani showed signs of being affected by alcohol. We have the account from the other driver ... there is the evidence of the police officers. There is no reason to believe they had anything against Mr Cipriani.”

He added that the “position is simple” and the reading was given “following correct procedure on an approved machine at a police station”. He continued: “I am sure the machine was operating reliably, and I am sure that the lower reading in breath was 67.”

Cipriani had been out drinking and dining with other players at Eight Over Eight in Chelsea after England’s thrashing of the Barbarians on 31 May last year. He had two espresso martinis and a vodka cranberry at dinner, between 8.30pm and midnight.

He then went to a club for around half an hour, before going to a friend’s house. He left at 4am to have breakfast. The rugby player said he had a fry-up, as well as a “small champagne flute” and two more espresso martinis, within 45 minutes, before getting a cab to his car.

Cipriani said: “I was not drunk, I felt fine.” He also denied speeding.

He did not react as the verdict and sentence were announced in court.