Woudn't henryanum reduce the plant size? Leaves are 30 cm long...could it be insigne x boxallii?
No, there are many large henryanum colonies, henryanum can be up to 40 cm for each individual leaf and make massive clumps similar to esquirolei. Does not mean anything about the flower size, but I found that those giant plants are still giant after a few years in cultivation. There are colonies of coccineum that are very big as well btw, same size as esquirolei. Clearly there are at least 2 very different types of coccineum in Vietnam, big leaves brown flowers dull color, very small plants similar to helenae, a bit yellowish, with dark red flowers.
Add to that that the common type of villosum in North Vietnam can reach nearly a meter leafspan, a hybrid could be that big. About the dots vs. flush at the base of the leaves, I found out that it does not mean anything, some henryanum have dots, some have flush, some have small dots... and some can be confused with coccineum even.
Actually, since I have seen many 50cm leafspan Phal maculata a couple of week ago with many leaves, similar to a pot-plant phal, and with 40-50 cm branched flower spikes like a christmas tree, I start to think that anything is possible regarding plant size.
Same for helenae, there are 20-30cm leafspan plants, plenty. Still the flower size is not quite related, apart from some exceptions...