On September 10th 1897 Mr George Smith became the first person to be convicted of drink driving. Whist driving his taxi he crashed into a building.
There were no breathalysers or blood tests in those days. Police officers only knew that Mr Smith was drunk because he acted drunk and because he said he was, but what they lacked was a scientific way to prove someone was too intoxicated to drive, even if he wouldn't admit it. There would have simply been a decision made by a police officer that Smith was drunk and that was final. He pleaded guilty and was fined 25 Shillings.
Until subsequent legislation was brought in to force there was no power to impose a driving ban.