For younger viewers, in the olden days, the bottom club in the 4th was relegated (one only, in those days), but there was no automatic promotion into the league. Instead, a vote was held by the football league chairmen on who should be promoted. Very often, this would be the same club that had supposedly been 'relegated'.1
Old boys networks and brown envelopes stuffed with promises, no doubt.
1 I believe this is how it worked in general. I haven't actually checked it.
I have mixed feelings about the election system. I grew up supporting Maidstone United and was gutted when they failed to get elected to the league after winning the Conference in 1984. It seemed most unjust to the 11yo me!
After that, a new owner came in and spent a few quid on players, as well as promising to build a swanky new ground. Unfortunately, he never got planning permission for it, but this didn't stop him selling off the old ground to developers.
By the time they won the title again in 1989, the system had changed to automatic promotion, so they were guaranteed a place in the Fourth Division. And they managed to stay there for three years. However, this was only achieved with reckless spending by the owner. Add to that the fact that they were playing their home games at Dartford and it's amazing the club survived as long as it did - folded in 1992.
Looking back on it, I feel the election system might have kept the club where it belonged, in the Conference, and maybe prevented the owner from overreaching himself.
There's no doubt the system was hugely corrupt though!