The meaning and origin of the expression: Donkey's years

Donkey's years

What's the origin of the phrase 'Donkey's years'?

A query at the Phrases and Sayings Discussion Forum asked if the British slang term for 'a very long time' was donkey's years or donkey's ears. My first thoughts were, "donkey's years of course - what would ears have to do with it?".

It turns out that, although Donkey's years is now the more commonly used slang term when meaning 'a long time', donkey's ears, has been used that way too (although not very often) since at least the early 20th century. The English humorous writer Edward Verral Lucas used the phrase that way in his novel Vermilion Box, 1916:

"Now for my first bath for what the men call 'Donkey's ears', meaning years and years."

The clue there seems to be that Lucas write comic stories. 'Donkey's ears' wasn't used until well after the date that 'donkey’s years' had become established in the language and was only ever a jokey alternative form.

So, having found 'donkey's ears' to be a side-show, we now come to when and how did 'donkey's years' originate? It is now used as Cockney rhyming slang and the assumption that is made by many is that the expression was coined as such, making the rhyme between 'ears' and 'years'. That assumption is very likely to be wrong. Three things count against it.

1. It isn't backed by any known evidence.

2. The expressions use as Cockney rhyming slang is long predated by it being used in being used with no CRS connection. The first example of the expression 'donkey's years' that I can find in print is from The Salisbury Times, July 1876:

Didn't you ask him how long it had been in his possession?
I can't recollect that. I might have done so.
Didn't he say for years and years and donkey's years?

This is getting on for a hundred years earlier than any use of 'donkey's years' as rhyming slang, which isn't found in print with a rhyming slang connection until the 1950s.

3. Donkey's ears works as rhyming slang whereas donkey's years doesn't. In rhyming slang the last word of a short phrase is rhymed with the word that gives the slang meaning; for example, trouble and strife - wife, apples and pears - stairs, etc. It makes little sense for the phrase to have originated in slang form as donkey's years, as that would rhyme 'years' with 'years'.

'Donkey's years' is certainly in use as Cockney rhyming slang now but the evidence points to it being a back-formation, that is, an existing phrase that got taken up as rhyming slang later.

Donkey's years may have been chosen as a synonym for a long time simply because donkeys are long-lived animals. Lively Laddie, a donkey who had lived up to his name for many years while plying his trade on Blackpool Pleasure Beach was, until his death at age 62, a contender for the 'oldest living quadruped' title.