But she was cleared of the charge after claiming she had been sober when she arrived for work – and got drunk when she consumed a 35cl bottle of vodka in the space of an hour whilst in the ladies toilet. A female detective turned up at work so drunk she thought she had finished her entire four-hour shift after an hour, a court heard.Det Con Donna Montgomery, 51, had arrived for duty at 10am for her first day in a new role but within minutes she had asked for annual leave and by 11am was so drunk she mistakenly believed the time was 2pm.Shocked colleagues breathalysed her when she was seen wandering around the car park of Mather Avenue police station in Mossley Hill, Liverpool with the keys to her Audi A1 in her hand – claiming she had finished work for the day.Tests showed she was almost three times the limit with one officer finding a small bottle of vodka and empty cans of gin and tonic in her erratically parked vehicle. She also smelt heavily of perfume and had several bottles of scent in her handbag.–– ADVERTISEMENT ––At Wigan magistrates court Montgomery, from Crosby, a detective with Merseyside Police for 15 years faced trial charged with driving with excess alcohol. “I asked her to get into my car and the first thing I asked her when she got in was if she had been drinking. “She said she hadn’t. My plan was to get her into the station and find out what had gone on.”I could tell she was drunk because she was using a sing-songy voice to answer me and she thought it was 2pm when it was only 11am.” It is thought Merseyside Police are to hold an internal injury into the incident which occurred on January 30 after Montgomery started a new role in the force’s Economic Crime Unit.Det Insp Elaine Coulter told the hearing: “I was coming into the station a 10:56am when I noticed DC Montgomery.”She used to be a member of my team so I know her well. I knew that she had recently returned to work from a period of absence.”I asked her how she was and if she enjoyed the new job. She said she did and that everybody was lovely.”I asked her why she was going home so early and she said that she was finished as she was doing a 10am until 2pm shift – but I knew it was only coming up for 11am. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. Montgomery told the court she had been off work for three months with work-related stress Credit:Ricky Champagne/Cavendish Press Montgomery claimed she got drunk when she consumed a 35cl bottle of vodka in the space of an hour whilst in the ladies toiletCredit:Ricky Champagne/Cavendish Press Tests showed Montgomery had 100 micrograms of alcohol in 100 millitres of breath. The legal limit is 35mg.Montgomery told the court: “I had been off work for three months with work-related stress from where I was working at the time.”I was upset by what had happened and I started to drink more. I could have a bottle of wine a night. “On my first day in my new job, I was made aware that the person I was working with was on a training course – so I thought it would be an ideal opportunity at this point to take time off work.”After my annual leave was approved, I went to the toilet downstairs and I had some vodka in my bag which I drank – a 35cl bottle. “I drove to work after only drinking two glasses of red wine the night before. “The empty containers in my car was alcohol that I was hiding from my husband, they were meant to go in the bin.District Judge Mark Hatfield found Montgomery not guilty.