Walker, more fully Hookey (also Hooky) Walker, is an exclamation expressing incredulity. It was first recorded in Lexicon Balatronicum¹. A Dictionary of Buckish Slang, University Wit, and Pickpocket Eloquence (1811):
Hookee Walker. An expression signifying that the story is not true, or that the thing will not occur.
(¹ balatronicum: from balatron, meaning a buffoon, a contemptible fellow)
Various explanations have been proposed, but most of them are unlikely to be more than folk etymologies. John Badcock (floruit 1816-30), writing under the pseudonym of John Bee, gave one in Slang. A Dictionary of the turf, the ring, the chase, the pit, of bon-ton, and the varieties of life, forming the completest and most authentic Lexicon Balatronicum hitherto offered to the notice of the sporting world (1823):
Hookey, Hookey Walker—and ‘with a hook,’ usually accompanied by a signiﬁcant upliftment of the hand and crooking of the fore-ﬁnger, implying that what is said is a lie, or is to be taken contrary-wise. One tells a long-yarn-story that asks for the disbelief of his auditory; whereupon another cries out ‘Hookey Walker!’ having previously shewn the sign above described, or another more elaborate still, which may be looked upon as a counter-sign, viz. spread the ﬁngers of both hands wide open, apply one thumb to the tip of the nose, and the other to the point of the little ﬁnger of the ﬁrst hand—this signiﬁes a clincher. History: John Walker was an out-door clerk at Longman, Clementi, and Co.’s in Cheapside, where a great number of persons were employed, and ‘old Jack,’ who had a crooked or hook nose, occupied also the post of spy upon their aberrations (which were manifold). Of course, it was for the interests of the surveillants, to throw discredit upon all Jack’s reports to the nobs of the ﬁrm, and numbers could attest that those reports were fabrications, however true; Jack was constantly out-voted, his evidence overlaid, and of course disbelieved, when his occupation ceased, but not so the fame of ‘Hookey Walker.’
T. W. Hill mentioned two other possibilities in Notes on the ‘Pickwick Papers’ published in The Dickensian² (summer 1948):
a London Magistrate with a hooked nose that gave the title of “beak” to all magistrates
an aquiline-nosed Jew named Walker who lectured on Astronomy and invited his pupils to “take a sight” at the heavenly bodies; the doubting pupils imitated behind his back his actions in “taking a sight” [= putting the thumb to the nose and stretching out the fingers] at his nose.
² The English novelist Charles Dickens (1812-70) used the exclamation Walker for instance in A Christmas Carol. In Prose. Being a Ghost-Story of Christmas (1843):
“Do you know whether they’ve sold the prize Turkey that was hanging up there?—Not the little prize Turkey: the big one?”
“What, the one as big as me?” returned the boy.
“What a delightful boy!” said Scrooge. “It’s a pleasure to talk to him. Yes, my buck!”
“It’s hanging there now,” replied the boy.
“Is it?” said Scrooge. “Go and buy it.”
“Walk-ER!” exclaimed the boy.
“No, no,” said Scrooge, “I am in earnest. Go and buy it, and tell ’em to bring it here, that I may give them the directions where to take it. Come back with the man, and I’ll give you a shilling. Come back with him in less than five minutes, and I’ll give you half-a-crown!”
A Christmas Carol: The Public Reading Version (1971), edited by Philip Collins, contains the following:
“Dickens as the boy,” recalled Rowland Hill, a Dickensian who saw him read A Christmas Carol many times, “put his thumb to his nose, and spread out his fingers, with a jeer, at the syllable ER [of Walk-ER]. This was a common way to call their pals ‘Fools’ without using the word.”
The most plausible origin was given by the Scottish writer Charles Mackay (1812-89) in the chapter titled Popular follies in great cities of Memoirs of Extraordinary Popular Delusions (1841):
Hookey Walker, derived from the chorus of a popular ballad, was also high in favour at one time, and served, like its predecessor, Quoz³, to answer all questions. In the course of time the latter word alone became the favourite, and was uttered with a peculiar drawl upon the first syllable, and a sharp turn upon the last. If a lively servant girl was importuned for a kiss by a fellow she did not care about, she cocked her little nose, and cried “Walker!” If a dustman asked his friend for the loan of a shilling, and his friend was either unable or unwilling to accommodate him, the probable answer he would receive was “Walker!” If a drunken man was reeling along the streets, and a boy pulled his coat-tails, or a man knocked his hat over his eyes to make fun of him, the joke was always accompanied by the same exclamation. This lasted for two or three months, and “Walker!” walked off the stage, never more to be revived for the entertainment of that or any future generation.
(³ quoz: an exclamation expressing incredulity or contempt)
There was indeed a broadside ballad of Hookey Walker, but it has not been securely dated earlier than around 1850. It thus begins and ends:
Spoken.—How do you do gentlemen? you don’t know me, I thought not. My name is Hookey Walker.
Just call at my lodgings between two and four,
And you’ll see “Hookey Walker” wrote over the door.
However, there is ample evidence that the name was in popular use in the early 19th century. For example, the Morning Advertiser (London) of Tuesday 3rd August 1819 reported that the night before, at the Lyceum Theatre, had been performed for the first time Walk for a Wager, or a Bailiff’s Bet, a musical farce in which two of the characters
are a London bailiff and his follower. The tricks and cant of those respectable members of society are brought into the country, where the bailiff goes upon what he calls a double ‘spec’, to pay his addresses to a lady, and to cheat a butcher by a wager, in which he introduces his follower, Mr. Hookey Walker, as a first-rate goer, and helps him to win by removing a milestone. The whole time of the performance of this Piece is occupied by Mr. Hookey Walker, in walking, and many scenes irresistibly ludicrous take place.
Similarly, The Examiner (London) of Sunday 13th May 1821 announced that the following day, at Sadler’s Wells Theatre, would be performed
a New Burletta [= musical farce], called HOOKEY WALKER, OR EIGHT MILES AN HOUR; HOOKEY WALKER, by Mr. WILKINSON, who will give a description of his own and Family Misfortunes.
Hookey Walker was also the name of a highly celebrated bay hunter. This horse was known to leap thirty-five five-barred gates in one day; and in the grand steeplechase, near Newcastle, it jumped the Great Burn, twenty-seven feet of deep water, and won the race easily. It died in April 1824.
Finally, Hookey Walker was the pseudonym of a correspondent to the London Magazine and Review of January 1825.
However, none of this evidence antedates the earliest use of the exclamation.