The phrase leather and prunella, also leather or prunella, is used of something of no value, of something to which one is utterly indifferent.

This phrase derives from a misinterpretation of the following passage [lines 183-194] from An Essay on Man. In Epistles to a Friend. Epistle IV (London: Printed for J. Wilford, 1734), by the English poet Alexander Pope (1688-1744):

Honour and Shame from no Condition rise; [183]
Act well your part, there all the Honour lies.
Fortune in men has some small diff’rence made, [185]
One flaunts in Rags, one flutters in Brocade,
The Cobler apron’d, and the Parson gown’d,
The Fryar hooded, and the Monarch crown’d.
“What differ more (you cry) than Crown and Cowl?”
I’ll tell you, friend: a Wise man and a Fool. [190]
You’ll find, if once the Monarch acts the Monk,
Or Cobler-like, the Parson will be drunk,
Worth makes the Man, and Want of it the Fellow;
The rest, is all but Leather or Prunella. [194]

In this passage, Alexander Pope is saying that honour—or lack of it—is unconnected with social condition, that inner worth is unrelated to the outer signs indicating the positions in society, and which are here represented:
– on the one hand by leather, which refers to the trade of a cobbler (here, leather denotes the material from which a cobbler’s apron is made—cf. “Cobler apron’d”, line 187);
– on the other hand by prunella, which refers to the profession of a parson (here, prunella denotes the material from which a clerical gown is made—cf. “Parson gown’d”, line 187).

This is supported by the following from From my own Chambers—probably by Henry Stonecastle, pseudonym of the British naturalist, poet and newspaper editor Henry Baker (1698-1774)—, published in The Universal Spectator, and Weekly Journal (London, England) of Saturday 26^th January 1745:

The Author of the Essay on Man knew Human Nature too well to suppose, that a Crown or a Cowl, an Apron or a Gown did of themselves constitute any Difference in the Inward Habit; and therefore he makes the Distinction of Characters to lie between Wisdom and Folly, and the greatest human Excellence to consist in acting well our Part.
You’ll find, if once the Monarch acts the Monk,
Or, Cobler-like, the Parson will be drunk,
Worth makes the Man, and Want of it the Fellow;
The Rest, is all but Leather or Prunella.

The earliest occurrences that I have found of the phrase leather and prunella, also leather or prunella, are as follows, in chronological order:

1-: From The Leeds Intelligencer (Leeds, Yorkshire, England) of Tuesday 19^th July 1785:

SATURDAY’s POST.
LONDON, July 14.

[…]
The Lords seem to get through the Irish propositions with rather more expedition than was first supposed. But after the examination at the bar of both Houses, and after all the speeches which have been spoken, and the mass of reasoning employed, very few doubts can remain for them to solve. After what has been said,—All the rest is leather and prunella.

2-: From The Dublin Evening Post (Dublin, County Dublin, Ireland) of Thursday 26^th April 1792:

POLITICAL REVIEW OF AFFAIRS ABROAD.

[…]
Whom have the Emigrants now to head them? The late King of Sweden, full of fire and military talents, a man besides of address and elocution, was undoubtedly a fit chief for such an undertaking.
As to Conde, he has never yet distinguished himself much in the science of war; Bouille is growing too old, and for the rest, they are little more than “leather and prunella.” These considerations, it is to be hoped, will prevent the rivers of blood which might otherwise be shed in attempting a counter-revolution.

3-: From an essay on theatre, published in The Morning Post (London, England) of Friday 18^th September 1807:

The defects of the under actors are general and incurable. Till each acts, even in what is called the lowest parts, as if the illusion depended as much upon him, as upon the foremost figure in the drama, it is idle to look for any thing approaching to a perfect representation. This is a change which “sun shall never see;” and, therefore, for ever is the English, destined to be inferior to the French Stage. It is not want of talents, it is the absence of professional pride, that is the bane of theatrical excellence. As long as no more liberal properties enter into the actor’s ambition, than merely to keep his station for the sake of the shilling on the Saturday, the Stage, in the mass, will continue to be little else than “leather and prunella.”

4-: From The Globe (London, England) of Tuesday 29^th November 1808:

It would appear that Episcopacy seems to gain great ground in Scotland; and that it becomes now, in these enlightened and liberal times, very agreeable to vast numbers of respectable and leading persons in that country, who constantly and zealously attend its very numerous chapels.
Money makes the man, want of it the fellow,
All the rest is leather and prunella.
So said a great author, and so say I; therefore I advise all those, who think with me, to lose no time. The Lottery Wheel may be said to contain the very essence of life, for in it are to be found Prizes of Twenty Thousand, Ten Thousand, Five Thousand, One Thousand, &c. &c. &c. besides two Extra Prizes of 500 Whole Tickets each, by which £100,000 may be gained. It goes round on Tuesday, 13^th of December.      Lovegold.

 

FOLK ETYMOLOGY

 

In Dictionary of Phrase and Fable, giving the Derivation, Source, or Origin of Common Phrases, Allusions, and Words that have a Tale to Tell (London: Cassell, Petter, and Galpin, [1870]), the English educationist and lexicographer Ebenezer Cobham Brewer (1810-1897) misunderstood the meaning of the noun prunella in the phrase leather and/or prunella:

Leather or Prunello. It is all leather or prunello. Nothing of any moment, all rubbish. Prunello, or prunella, is a woollen stuff, used for the uppers of ladies’ boots and shoes.
Worth makes the man, and want of it the fellow;
The rest is all but leather or prunello.
Pope, “Essay on Man,” iv.

In her column Mind your language, published in The Spectator (London, England) of Saturday 24^th July 2021, Dot Wordsworth criticised as follows the entry in Brewer’s dictionary—but, in fairness (although it is true that Brewer is often untrustworthy), the misinterpretation of the passage from Pope’s Essay on Man predates this dictionary:

The phrase leather and prunella […] used to be deployable to any middle-class readership. George Eliot and Anthony Trollope both used it, in the sense ‘a matter of indifference’. I expect both knew it originated in the poetry of Pope, but that is not quite what he meant.
This 19^th-century meaning is to be found in Brewer’s Dictionary of Phrase and Fable. That compendium is extremely unreliable on word origins, but useful in telling us what Victorians thought were their origins, sometimes based on false history. […]
[…]
[In An Essay on Man] prunella is nothing to do with women’s boots, but is the strong cloth for making clerical gowns (just as in the 18^th century, they began to speak of ‘men of the cloth’). Leather and prunella are certainly not ‘rubbish’ in Pope’s phrase. Never trust Brewer.

The same misunderstanding of the meaning of the noun prunella occurred in the column John Chatham’s Gossip, published in the Illustrated Leicester Chronicle (Leicester, Leicestershire, England) of Saturday 8^th May 1948:

In response to my request to readers for picturesque phrases, Mr. Ronald Pollock, who was for some years in the shoe industry, sends the expression “leather and prunella.”
To workers in the trade, prunella will be familiar as the name given to a cloth used in making uppers, and “leather and prunella” signifies something which is superficial or non-essential.