I was posh, I had a battery powered float for tench and bream. Only problem was staring at it in the dark and your eyes would cause the float to 'wander'. It wasn't the float moving but your eyes as you stared at one spot.
I must admit ledgering on the river was almost always done with white tape round the rod tip up into the ambient light, and/or touch ledgering.
Brings to mind an amusing story with the battery float. I put the batteries in for the start of the season, and went to check the shotting with a bare hook in daylight, a size 10 Drennan Sweetcorn hook. Chucked it in, float went under, "oh puffle, too much weight", reeled in and discovered myself playing a 4oz roach. That night I think I had 4 tench on the float up to 6lb, all males.