"it should be remembered that there was no such thing that could be accurately referred to as "British Military" prior to 1707."
Maybe - although the Stuart kings styled themselves as "of Great Britain," so Prince Charles' little party are not ruled out. But, I agree that the refrain of "True British sailors" definitely points to a time when Britain was a working entity, rather than just a union in law - so that points to later rather than earlier in the C18th. (And I am only ignoring for my own amusement the SOLE RELEVANT FACT in this discussion as given by Jack Campin.)
You over-exaggerate the continued hostility of Spain to England. There was plenty of trade between the two countries, fluctuating of course with the hot or cold of the relationship between the two countries. (Since you love my musings so much, I shall mention my Great-Uncle John, who, in 1577, was given a job as Gunner - at 8 ducats a month, no less - by the King of Spain for having brought 258 Christian men out of slavery in Alexandria. Old John Fox probably wrote the original "Spanish Ladies" while returning freely to England in 1579, and listing off, one by one, those landmarks so often remembered and longed for.)
"Who ever made the claim that the song was used by pilots and masters of vessels as a navigational aid? "
The poster immediately before me made just that claim. "The landmarks and distances in the song are the references pilots and sailing masters would have used to bring their vessels home in the days before electronic navigation."
But whether intended for navigating, or teaching navigation, or teaching how to bring a ship to anchor, the song is pretty useless, especially since different versions (all beginning "Farewell and Adieu etc") give different distances and procedures. (Although, if we didn't both agree on the later date of the song, I might have accepted the argument that Cloudesley Shovell's little accident was down to a confusion on the part of some hapless middy who happened to know the wrong version of "Spanish Ladies.")
However - all absurdities apart - I see no arguments in this thread to counter the view that "like the songs of Dibdin and all the rest, the song was quite likely the work of an armchair enthusiast whose closest link with Spain was a pint of sherry in a tavern in Deptford."