The recipe containing plaster of Paris is the very original Purdey stockers recipe used to fill the grain on new stocks.
I very rarely use the plaster ingrediant nowadays.Preferring to spend time filling the grain with wax and oil by applying numerous coats of oil until the desired level is reached.
The Napier is very good for a quick finish but is not a 'true' London finish.It contains urethanes, gives a high gloss but very 'varnishy' type of finish.I think most of you are slipping up and putting far too much wax in the recipes.If you want a hard finish use Carnubua, if you want a traditional finish use beeswax. But you can do without both.