S.J. Adair Fitz-gerald writes in his book Stories of Famous Songs Vol 1, c. 1901, pp. 227ff:

A SIMPLE, homely song that is rarely heard now-a-days, for its novelty has long worn off, is " The Postman's Knock," written by L. M. Thornton, and composed by W. T. Wrighton, of drawing-room ballad composing and singing celebrity. "The Postman's Knock," when it was first published, about forty years ago, spread into favour at once, and was sung all over Eng-land, because it appeared at a period when the " New Penny Post" of Rowland Hill had had time to become understanded of the people and to be utilized by them. And because it appealed to the sympathies of the majority, it remained quite a favourite in some parts of the country for more than twenty years. The words were written by a humble individual of small literary ability, who died in the Bath Workhouse, May 8th, 1888, after a hard fight against poverty. It must be confessed at once there is no art whatever in the irregular stanzas of the song, but there is plenty of human nature of a kind:

"What a wonderful man the postman is,
As he hastens from door to door !
What a medley of news his hands contain,
For high, low, rich, and poor !
In many a face he joy doth trace,
In as many he gnefs can see,
As the door is ope'd to his loud rat-tat,
And his quick delivery.
Every morn, as true as the clock,
Somebody hears the postman's knock.

"Number One he presents with the news of birth,
With tidings of death, Number Four,
At Thirteen a bill of a terrible length
He drops through the hole in the door.
A cheque or an order at Fifteen he leaves,
And Sixteen his presence doth prove,
While Seventeen does an acknowledgment get,
And Eighteen a letter of love."

Properly speaking, the love-letter should have been left at Seventeen, but perhaps Mr.Thornton was above punning. It should be remembered that a letter in those days was quite an event, for before the introduction of Sir Rowland Hill's "Penny Post," letters were very expensive luxuries indeed. For one to receive a letter, in country parts, was to be converted into a kind of hero for the time being, and to be worshipped accordingly. Letters from oversea were almost unknown except amongst the well to do, and friends and relations who lived at a distance rarely heard of each other from one year's end to another. Now for the last verse:

"May his visits be frequent to those -who expect
A line from the friends they hold dear;
But rarely, we hope, compelled he will be
Disastrous tidings to bear.
Far, far be the day when the envelope shows
The dark border shading it o'er;
Then long life to Her Majesty's servant, we say,
And oft may he knock at the door !"

Let us not be too captious over the poverty of idea here exposed, nor criticise too harshly the falseness of the metre and the weakness of the rhyme. L. M. Thornton knew his audience, and wrote level to them, and being of a homely nature himself, he knew exactly the chords he could play upon with the best results. Thornton wrote many other lyrics that were more or less popular as, for instance, " Pleasure," " Smiles and Tears," " Sing on, Sweet Bird," " Look Up," and the sacred songs, "As One by One our Friends Depart," and " Rest for the Weary," the music being composed by W. T. Wrighton. "The Postman's Knock" was so widely known and sung, that John Baldwin Buckstone had a piece written on the subject for the Haymarket Theatre. On April ioth, 1856, he produced a musical farce, concocted by L. M. Thornton, of which the " Illustrated London News," of April 19th of the same year, says: "A new farce, called ' The Postman's Knock/ somewhat rudely constructed, for the apparent purpose of introducing the song so named, has been pro-duced at this (Haymarket) Theatre. The song itself is well sung by Mr. Farren ; and the piece aided by his talent, and that of Miss Lavine and Miss Schott, who also sing a ballad or two each, has been favourably received." The programme for the week at the Theatre Royal, Haymarket, is worth giving: " Monday, April 7, and during the week, the new and successful comedy,' The Evil Genius ,' after which the renowned Spanish Dancer, Perea Nena, who, with Manuel Perez and a New Company, will appear in the New Ballet-Pantomime of ' El Gambusino; or, The Mexican Gold-Digger,' after which, on Monday, Tuesday, and Wednesday, for the Last Three Nights, ' Lend Me Five Shillings' (Buckstone as Golightly); on Thursday a New Farce called ' The Postman's Knock.' " But the piece was first tried at the Surrey Theatre on the 7th of the same month with Phelps and Voltaire in the cast.