It had been introduced to curb the number of road fatalities and serious injuries where alcohol had played a factor, which then numbered around 13,000 a year.

The limit was set at 80mg of alcohol per 100ml of blood, a threshold still in place today.

Before its introduction, drivers thought to have been drinking too much had to undergo a series of roadside tests, similar to those used on suspected drug-drivers today.

Early breathalysers were, if not exactly cumbersome, certainly not the easiest pieces of kit to use.

Officers had to assemble them by the roadside and then any positive result had to be backed up by a blood test.

Since then, the breathalyser has undergone a revolution, with digital versions now in use.

And the number of deaths annually on the UK’s roads involving alcohol is down to 540, despite a far greater number of vehicles.

But since the end of the 1990s, the number of deaths caused by drink-driving has been creeping upwards.

Another problem facing police is the number of people coming to Britain to work, whose home country may have different drink-live laws.

It’s the breathalyser that will play a key role in reversing that trend.

Years of high-profile campaigns have made drink-driving socially unacceptable, but there are still too many drivers prepared to risk their licences, livelihoods and even their lives by getting behind the wheel while over the limit.

Traffic police now test every driver they stop, whether they have been involved in an accident or not.

And, as drivers with alcohol in their system are more likely to be more erratic, it means they’re more likely to get pulled over.

The Royal Society for the Prevention of Accidents played a key role in promoting the need for drink-drive legislation in the 1960s and no want to see the limit reduced.

“It is now time for renewed action,” said Kevin Clinton, RoSPA head of road safety.

“RoSPA is calling for the drink-drive limit to be reduced to 50mg of alcohol per 100ml of blood — a move which would save around 65 lives and 230 serious injuries on Britain’s roads each year.”