Dear Mark,
I must say i am smashed with such imense input, which will take me ages to digest.
One thing comes out of my residual knowledge, though; it looks more plausible that Spaniards (and Portuguese) copied British models than the other way round ... specially (or specifically) within this period, as already approached.
In the meantime i dare post some random details on the subject, to either enlighten it a bit or, which is more probable, add it further complexity.
In his work ARMAMENTO PORTATIL ESPAÑOL 1764-1990, Marceló Rubi illustrates and describes a SABLE DE ABORDAJE (boarding cutlass), with overall characteristics similar to the British P1845, except for the shallow blade fullers and the turning of the guard top (i miss the correct term
).
There is no certainty as to the date of this model but, as the example exhibited at the Toledo Factory reads 1859, it is thought such is the date of this pattern.
.