The phrase curate’s egg means something that has both good and bad characteristics or parts.
It is an allusion to True Humility, a cartoon by George du Maurier*, published in Punch, or the London Charivari of 9th November 1895. This cartoon depicts a meek curate who, having been served a stale egg while breakfasting with his bishop, tries not to offend his host; it has the following caption:
Right Reverend Host. “I’m afraid you’ve got a bad Egg, Mr. Jones!”
The Curate. “Oh no, my Lord, I assure you! Parts of it are excellent!”
Of course, a stale egg is bad all through, and the cartoon makes fun of over-dutiful, or self-serving, deference.
* George du Maurier (1834-96), French-born novelist, cartoonist and illustrator; author of Peter Ibbetson (1891) and Trilby (1894); grandfather of Daphne du Maurier (1907-89), English novelist, author of Jamaica Inn (1936) and Rebecca (1938)
The earliest reference to the cartoon that I have found is from the Edinburgh Evening News of 19th May 1896:
“THE RECKONING” AT THE THEATRE ROYAL.
“The Reckoning” is a stranger to Edinburgh, which probably explains the small house which received it at the Theatre Royal last night. It is a disappointing play, but that is because it promises so well to begin with. Like the curate’s egg at the Bishop’s breakfast table, it is very good indeed—in parts.
The earliest instance of the phrase is from The Graphic (London) of 2nd January 1897:
The holiday season passed off most successfully, for, like the curate’s egg, the weather was in parts excellent. On Christmas Eve it rained heavily, but Christmas Day was fine and still. Boxing Day, however, was a miserable day, but Sunday followed the example of Christmas and was bright and spring-like. Richmond and other places in the suburbs were thronged with holiday-makers, and on the evening of Boxing Day there was not a seat to be had in any theatre or other place of amusement. Holiday charges were fairly light, though in some parts of the town the gloom of Boxing Day led to several appearances in the Police Courts on Monday.
Interestingly, an allusion to the cartoon appeared in the magazine Punch itself on 1st September 1909; in a story titled Old Jokes for New, a humorist dreamt that he “had reached a land where the old jokes were unknown”:
I climbed the stairs to the editor’s office [...]. I do not remember the name of the country, or how I got there; but I was far from the land of my birth, in a place where the prospect of a fresh start filled me with hope.
I was assuring the editor that I could do all the things the London editors had mistakenly decided that I could not do, when he interrupted me:
“What we want is something fresh,” he said, “new treatment, novel points of view, bright ideas, and”—with a wave of the hand—“and so on.”
“Exactly, just my line,” I said.
“Take my ‘Wit and Humour’ page, for instance. It’s so difficult to get out of the old ruts, away from the old stories—”
“I know—the curate’s egg, and the rest of ’em,” I said.
“The curate’s egg? I don’t understand.”
“I mean the story—the story of the curate’s egg, you know; ‘parts of it excellent,’ you remember.”
“No, never heard it. Is it a good one?” he asked. So I told it to him. He laughed loud and long, slapped his leg, and summoned his assistant, to whom he repeated it. I began to wonder whether I was dreaming. However, I was encouraged to try again, and I recounted the incident of the man who attempted suicide on the metals of a slow line, and died of starvation before a train came, following with the tale of the nervous page-boy at the Bishop’s bed-room door. They were convulsed.
“Young man,” said the editor, wiping away his tears, “I’ll pay five pounds for a column of stories like those.”
“Done!” I said. “And could you do with a couple of thousand on the Mother-in-law?”
“No, Sir; humour’s your line. You stick to humour.”
“But she is humorous,” I replied.
“Not in this country,” he declared grimly. So I told him a mother-in-law story. His face lit with the light of a new discovery, and he ordered two columns, adding that the boys would enjoy reading it. It required great restraint on my part to reserve the Scot for a future suggestion.