Mylands is a shellac based based friction polish. I have seen recommendations to apply a carnauba wax top coat after applying. That is all I know to be factual. Other things I have seen said that it is basically 1/3 shellac, 1/3 boiled linseed oil (BLO) and 1/3 denatured alcohol (DNA).
Personally, I do not like using Mylands. The finish isn't honestly any better than anything else and the mixture gets sticky which makes it harder to work with.