The result was endless images of stars like Bon Jovi with a can of the Dutch beer in their hand (and a few of the crates reserved for the crew and production team as way of recompense, of course).
At the time it seemed obvious, and might well have been illegal, but since no money changed hands, it probably sneaked in within the rules of commercial television at the time.
Fast forward to today and it's blatantly obvious that shows such as '24' are chockablock full of product placements, as are so many movies (the Bond franchise being a particularly brazen version of the practice).
News that product placement restrictions are to be relaxed on British TV is therefore somewhat a case of closing the stable door after the event.. However, it is sensible and does recognise the need to provide multiple sources of revenues in the dollar to cents world of TV2.0.