FIFTY years ago police carried out the first roadside breath test on a motorist in Britain and since the introduction of breathalysers the number of road fatalities attributed to alcohol has plummeted.

That first ‘blow in the bag' test took place on a motorist in Shropshire on October 8, 1967.

Prior to that, the criteria for prosecution was less scientific - whether you could touch your nose with your eyes shut, walk in a straight line or stand on one leg.

Back in 1967 there were 1,640 road fatalities attributed to alcohol. Since then, there's been an eight-fold reduction in the number of deaths alongside a dramatic increase in car ownership.

However, 200 people a year still die in accidents where at least one driver is over the alcohol limit according to the latest statistics available from the Department for Transport.

Final figures for 2015 show a nine per cent increase in the number of seriously injured casualties - from 1,070 in 2014 to 1,170 - the first rise since 2011.

The totalnumber of casualties in drink drive accidents for 2015 was 8,470 - up three per cent on the previous year.

Police carried out more than half a million (520,219) roadside breath tests in 2015, the lowest number since data collection began in 2002. More than 60,000 drivers - one in eight of those tested - failed or refused to take the test.

Men were twice as likely as women to fail a breath test, a trend that was consistent across all age groups according to the DfT report.

The Road Safety Act of 1967 set the maximum limit at 80mg of alcohol per 100mL of blood which is 0.35mg of alcohol per litre of breath. It became an offence for the first time to be in charge of a motor vehicle with a blood or breath alcohol concentration exceeding that limit.

"It seems remarkable now that the new law was greeted with outrage in some quarters, with publicans heckling the then Transport Minister, Barbara Castle, accusing her of damaging their trade," said Hunter Abbott, an advisor to the ParliamentaryAdvisory Council for Transport Safety and managing director of breathalyser firm AlcoSense Laboratories.

"In the first 12 months alone, there were 1000 fewer deaths and 11,000 fewer serious injuries on the roads - proving that the use of the ‘drunkometer' was both necessary and justified".

The original breathalyser was a relatively crude device, initially used to confirm a policeman's suspicion that a motorist was under the influence. A subsequent blood or urine test at the police station provided the evidential proof.

The fuel cell alcohol sensor was later developed, an electronic device that transformed the process of screening by providing the police with a quick test to accurately quantify the driver's alcohol level at the kerbside. For prosecution a second evidential test needed to take place at the station using a second, more precise method than used at thescene.

Until the 1990s this involved blood or urine testing at the station which required a doctor to be called out to take the sample. If a doctor was unavailable, sometimes a driver could escape prosecution. The process was dramatically simplified with the invention of evidential infra-red breath testing at the station, offering comparable accuracy to blood testing - removing the need for a doctor to be called out and improving the prosecution rate.

"There are still more than 5,000 accidents a year where at least one driver is over the alcohol limit,and nearly a fifth of drink drive convictions are the morning after the night before," added Mr Abbott.

"Studies also show that if you drive while having only one-eighth of the English drink drive limit in your system (one fifth of the Scottish limit), you are 37 per cent more likely to be involved in a fatal accident than when sober.

"The only way totell when you're safe to drivethe morning after is either to abstain completely or to use an accuratepersonal breathalyser."

Such breathalysers, including the AlcoSense Excel are fitted with a smaller version of the sensors used by many police forces and give a detailed reading of an individual's blood or breath alcohol concentration.