There are not many women who pour themselves shots of vodka first thing on a Monday morning while working behind the bar of a pub.

Jo Stokes has done it on a regular basis in almost every pub in the east of Brighton. Sometimes her tipple is whisky, other times gin. Sometimes she buys three double measures in one go.

But Jo is not doing it for personal pleasure - she is working.

She is a senior trading standards enforcement officer with Brighton and Hove City Council. One of her responsibilities is to go into pubs and check the booze we buy for quality and quantity.

Armed with a small official-looking black box containing a range of glass receptacles and pieces of equipment which would be at home in a chemistry laboratory, she gets to work behind the bar of the Duke of Beaufort in Queen's Road, Brighton.

She selects a tall cylindrical glass and pours a measure of vodka into it from one of the optics behind the bar. It proves to be a correct measure - customers at the watering hole are getting the right amount of booze in their glasses.

She then holds a thermometer into the spirit before dropping in a small floating spirit hydrometer and consulting a booklet of complicated looking tables which confirm the spirit had not been watered down. All is well at the Duke of Beaufort, although not every landlord is as honest as Adrian Street.

Jo has worked as an officer for 12 years, some of that time with other local authorities.

She said: "I did this test once, not in Brighton, and what appeared to be vodka was half water. Sometimes it may be a staff member who has been helping themselves to a drink and then watering it down to cover their tracks."

Jo also checks the Duke of Beaufort to ensure all the glasses have the Government stamp on them. The crown etched on the glass shows that they officially hold a pint or half pint.

Mr Street, who has been landlord of the pub for eight years, said: "I don't mind Jo being here. People shouldn't mind if they haven't got anything to hide."

Jo randomly visits each pub in her patch every two or three years. She is also able to visit any shop in the city of Brighton and Hove to check items being sold comply to legal safety requirements, enforce food labelling laws, check adverts are not misleading, prices and labelling, make sure petrol stations pumps are giving the right amount of fuel and ensure shops are not selling fags and booze to underage youngsters.

During her rounds this week, Jo also visited Dave Sutton, who has run DM Sutton Butchers in Warren Road, Woodingdean, for 19 years.

Putting on white coat and hat, Jo gets to work with another box of tricks, this time a set of weights. She checks Mr Sutton's two sets of scales are giving accurate measures. She checks the labels on all his packs of meat. By law they have to have a list of ingredients on them. The source of the meat must be traced back to a specific animal.

She also takes some products at random from the chiller cabinets and weighs them with her own set of scales taken from another black box she carries.

She sends off meat for analysis to make sure it matches its description.

Jo and her fellow senior trading standards enforcement officer also try to educate the public about their work. They spent Saturday at a festival in the city manning a stand and chatting to the public.

There are six enforcement staff working for the council, some of them working on undercover criminal investigations.

Jo Player, one of two principal trading standards officers with the city council, works mainly on criminal cases.

She is currently concentrating on seizing counterfeit goods such as fake branded clothing and bootleg DVDs which are being sold in the city.

The trading standards team has seized goods from markets and street sellers, who can all be prosecuted for breaking the law.

The team can work undercover gathering intelligence and evidence to take a case to court.

Jo said: "My type of work is more like CID whereas Jo's (Stokes) is more like bobbies on the beat, more routine visits whereas we do investigations."

In the year 2001/02 the team dealt with 6,114 complaints and inquiries from consumers and traders; visited 2,484 premises; issued 38 formal cautions/ written warnings; and prosecuted nine traders as a result of investigations by officers.

The team is also concentrating on rogue car traders who place cars on the sides of roads in the city and offer them for sale. Buyers think they are making a private sale when, in fact, the seller is a trader but because they are buying from an apparently private seller the purchaser has fewer rights.

They are also targeting door-to-door sellers and bogus callers.

It is a job which means they rarely switch off. When they shop for pleasure, they cannot help but look at labels, prices and advertising to ensure they are all legal and that the city's residents are not being ripped off.

But Jo added: "We do also rely on the public to be our eyes and ears."

The department has a web site with information for consumers and their rights which can be accessed on www.tradingstandards.gov.uk/brighton-hove or phone 01273 292522.