Plumb puddings or plum puddings?

Today I visited the Napoleon exhibition at the National Gallery of Victoria. It was presented in a fascinating way so that visitors had a sense of experiencing the story of the French Revolution and the rise and fall of Napoleon.

 Having a keen interest in words, I was surprised to see a James Gillray cartoon from 1805 titled The Plumb Pudding in Danger. It is a caricature of the English Prime Minister of the time, William Pitt, slicing up the world, sharing with Napoleon Bonaparte.

 The modern spelling of this dish is plum pudding. I've never taken notice of the fact that there are no plums in it. So I wondered whether the spelling plumb is a more accurate one.

  The Free Dictionary quotes the Farlex Trivia Dictionary:

plum pudding - So named because it was originally made with plums—the word was retained to denote "raisin," which became the main ingredient.

An article from The West Australian newspaper Sat 31 December 1935 refers to an eighteenth century recipe for a boiled 'plumb pudding'.

What's Cooking America , giving an overview of the history of the name, says there were never plums in plum pudding.

In researching this post I became aware of another thing I've never paid attention to - we use the word prune to refer to dried plums. The Online Etymology Dictionary says plum comes from the Latin pruna, and that the change of Latin pl words to pr is unique to the Germanic languages:

plum (n.) O.E. plume, early Germanic borrowing (cf. M.Du. prume, O.H.G. phruma, Ger. Pflaume) from V.L. *pruna, from L. prunum "plum," from Gk. prounon, later form of proumnon, from an Asiatic language. Change of pr- to pl- is unique to Germanic. Meaning "something desirable" is first recorded 1780, probably in reference to the sugar-rich bits of a plum pudding, etc.

The prunus trees that are so lovely and so useful in our gardens include the plum, of course, but I also love cherries and apricots.