OF THE MANY ROGUES and scoundrels who prowl the pages of this amusing book, my favorite is Lord William Paget. He was born in the spring of 1803, the son of Henry William Paget, Earl of Uxbridge, a gentleman and military commander described by one admirer as "the most perfect hero that ever breathed." But his heroism was of little avail in the battle he was to wage for the following half-century against the profligacy of his younger son--"this disgraced and wretched young man," in his father's words--and the mountain of bad debts he accumulated. Not merely was William a wastrel, but he was a cheeky one to boot, as suggested by this reply to one George Thompson, a lawyer attempting to represent a creditor named J. Curwen:

"Sir, on looking over some paper this day, I find one from you, dated 4 May last upon the subject of Mr. Curwen's bill. I do not recollect to have seen it before, and certainly a more laughably impertinent production I never received. Who you are, for you sign your name George Thompson (there are a great many George Thompsons in the world) dating your letter (if it deserves the name) Dublin, I am at a loss to guess; neither should I be at the trouble of finding out, excepting for the purpose of informing you, that the next opportunity you give me, I shall give you the benefit of your postage of your letter-back again. P.S. Mr. Curwen's bill (by the way) is an impudent extortion, whether I undertook to pay it or not."

William Paget was a black sheep, one of those "sons or daughters who have, in the eyes of their parents or relations during their lifetime, or of their posthumous descendants, brought disgrace upon their family." As Christopher Simon Sykes quite properly observes, "To the outsider, the person whose welfare does not rely on the wool being pure white, the black sheep of a flock is invariably the most interesting for the very reason that it is different." His study of the breed, written for a popular audience that should embrace it with enthusiasm, focuses on the British aristocracy. Not merely is this territory that Sykes knows well, but the fascination that the upper crust holds is undeniable: "the greater the escutcheon, the more violent the stain upon it," providing for those of us less fortunately situated delicious lessons in the mere mortality of the mighty.

Sykes believes that the phenomenon of the British black sheep can be traced to two broad influences: child- rearing customs in the upper classes and the practice of primogeniture. As to the former, Sykes believes that "countless young men" were "the victims of the age in which they lived, an age in which the upbringing of children seems to have been rooted in the Middle Ages." Not merely were infants given over to wet-nurses, many of them "cruel and neglectful," but as late as the 17th century "there was the practice of tight swaddling in the first months or even year of life, whereby babies, almost immediately after birth, were tightly bound in bandages so that they were unable to move either head or limbs." Add to this the prevailing violence at the boarding schools to which these boys were sent and you have the raw material for shaping emotionally stunted men who, "although they may have been extremely independent and self-assured, had little love left in their hearts, even for themselves."

This was especially true of younger sons, who were raised amid luxury and the constant attention of servants but were deprived, by primogeniture, of the wherewithal to sustain such a life as adults. They believed that the world owed them a living, but in most cases it was not forthcoming. As Sykes notes of the aforementioned William Paget: "He took it as a matter of course that all his debts should be paid at once and in full. They were after all no fault of his. He was a younger son with inadequate funds to finance a lifestyle to which he had become accustomed. He expected everyone to commiserate with him."

Within the circles in which he moved, to a considerable degree everyone did--with, of course, the notable exceptions of his father and his creditors. Many young men were in a similar fix--or, to be more accurate, what they chose to view as a fix--and they regularly conspired to ease each other's paths. Often, in fact, they formed predatory packs that were distinguishable from ordinary street gangs only by the tony garb and bearing of their membership. They drank to appalling excess, womanized, gambled--even indulged in what one 17th- century chronicler described as "the highest frolic . . . a genteel murder; such as running a waiter through the body, knocking an old feeble watchman's brains out with his own staff, or taking away the life of some regular scoundrel who has not spirit enough to drink and whore like a gentleman." These amusements frequently went lightly punished, if at all, by the law.

These amusements, that is to say, were not always amusing, and there is a dark center beneath the witty exterior of Black Sheep. The line between the harmless idler and the threat to society is a narrow one that these fellows often and blithely crossed. They decimated fortunes, ruined estates and art collections, made frivolous sport of the lives of others. That they had at their disposal so large a supply of "foolish tradesman and gullible women" is indeed a mystery, though there is none in the obituary that, written for but one among their number, serves for all: "Redeemed by no single virtue, adorned by no single grace, his life has gone out without even a single flicker of repentance; his 'retirement' was that of one who was deservedly avoided by all men."

The same cannot be said of Black Sheep. With the inexcusable exception of "lifestyle," it is literate, intelligent and graceful. Sykes relates a story well, and has many rich and revealing ones to tell--although those of the few women in these pages seem included more as gestures to the contemporary spirit of sexual egalitarianism than out of any genuine relevance to his story. Never mind. Black Sheep is a delightful book about some exquisitely loathsome people.