I did know of a chap back in the early sixties who swore by a black bead glued to the back of a size 18 (or was it threaded on?) with the hook painted white............That he caught was without doubt, but whether it was on the above is open to question!
If you think about it, not too much difference between a bead and a grain of hemp as far as hardness is concerned, but as Gerry says, the imitation jobbies does well enough these days.
Personally I think hemp as a bait, is much underated in certain conditions although getting the set-up correct with fine line/hooks and the bait cooked just right AND making time to get the roach/dace feeding on the stuff tends to put most people off.
I suppose I've always done better in the past with the hemp/elderberry combination (I nearly said 'combo', but I hate that 'word'!) alternating between the two and long trotting over distance...
Regarding the set-up, and these quirks tended to become unwritten 'law' among 'hempers' years ago, it was a given to use very fine lead wire in a coil (formed around a sewing needle) resting on the bottom shot to stop false bites as the fish (maybe) went for the bottom shot as it sank. It was very good though to get the float just right above the surface by removing tiny bits of the lead with scissors.
In hindsight bunching the shot together could do the same job but the lead coil was very popular and worked very well...
Great bags of roach around the Henley area all day long even in hot weather....
Happy days!!!