Smiley,
Could you perhaps be thinking of the long-gone "British Visitors Passport". This existed in various forms up until 1995 and was a simplified document available over the counter at the Post Office and valid for 1yr to most European destinations. I could never really see the point of it, but it was very popular at the time for cheap daytrips/package holidays.
In the true 'Duty Free' days, there were also so-called 'booze-cruises' where you never got off the ship, and therefore didn't need a passport of any kind, but could pick up your allowance on each leg of the journey.
I also know of quite a few people who (because there were no departure checks) found themselves abroad without their passport ..... and had little difficulty getting back into UK on the basis of a works photo-ID card! I wouldn't want to try that today!.