I am straying off-topic a bit here but, for what it is worth, when I have seen such plants there, I don't think the all the plants in some nurseries in The Netherlands, so labelled, are the x Gasterworthia 'Royal Highness' as described by Rowley NCSJ 1957, 12 (4), 74. Some look very much like x Gasteraloe rather thanTerry S. wrote: ↑Wed Jun 24, 2020 3:58 pm Compare with https://worldofsucculents.com/gasteralo ... -highness/. This is something that is propagated in quantity in at least one Dutch Nursery.
x Gasterhaworthia.
The plants below in my collection today originated from vegetative material first distributed by Rowley from plants received from the introducer Howard Gates from California in the 1950s are what I consider to be the true article. The amount of tubercles and leaf colour are quite distinctive.
Maybe a lot can happen in the intervening 65 years, particularly in the nursery trade?