Jim Slater, the former financial wonder boy here, will be characterized on Thursday as a crafty operator on Britain's unregulated stock exchanged on which he made millions by manipulating share prices.

A searching study by Charles Raw of the Sunday Times charges that Slater;

Got his grubstake from profits on stocks of obscure companies he praised in an anonymous tipster's column in the Sunday Telegraph.

Set himself up as an investment adviser and sold his clients shares in which he was speculatin.

Used accounting gimmicks to inflate profits, hide losses or conceal the extend of his control on satellite firms.

Speculated in stocks of firms he controlled, profiting from his insider's knowledge.

None of these actions, however, appear to violate British law because there is very little of it governing stock market dealers.

Slater, now 48, founded Slater Walker, the title of Raw's book. Until the firm collapsed in 1975. It was regarded as the hottest outfit in the City. Slater Walker was variously described as a congolomerate, a holding company and a bank, but according to Raw's excruciatingly detailed analysis of its transactions, Slater Walker "was basically a machine for generating stock market profits."

With its string of little factories, mutual funds, banks and even an insurance company, Slater Walker made money for a few insiders and their friends as long as shares prices rose.

"The rssence of (Slater's) techique," Raw writes, "was to trey to control the market - buyers, sellers and proces - so that he could realize profits at will." Desoite its confusing appearance, the company "was really about one thing: the manipulation of share prices."

Although Slater appeared on the cover of Time's European edition, his name is little known in the United States, where stock dealings are gorverned by the Securities and Exchange Commission. As Slater himself has written, its "regulations are a life's work to master."

Many techiques Raw ascribes to Slater would be outlawed by the SEC, but in Britain there is little regulation of stock dealings.

In Britain, Slater Walker was the most exciting name in British business fro nearly 10 years. Anthony Sampson wrote in his "New Anatomy of Britain" that Slater (like his partner, Peter Walker) "is the very paragon of the new Health-type Tory-self-made, hard-working, unsentimental competitive."

Indeed, former Prime Minister Health was a Slater client who profited from one inside deal, according to Raw, to the tune of about $50,000 in those days. There is no evidence that Health knew how the money had been made for him, but he did elevate Walker to a central ministry, Trade and Industry.

Walker left the firm when he went into the Health government in 1970. Slater resigned five years later when the Singapore government tried to extradite him to face criminal charges for his stock dealings there. A British court held that Singapore could not have Slater but could take one of his deputies instead.

Finally, the Bank of England steeped in and pumped about $140 million into the firm and guaranteed loans of another $80 million in an aooarent effort to protect crediters and stock-holders. The Bank also persuaded the Labor government not to conduct a public inquiry into Slater Walker's activities.

Slater is now dealing happily again, this time in real estate and on a large scale, even though he claims his debts are more than $1.4 million. The Raw book will not help him win clients, however.

It is also unlikely to further what had been the meteoric career of Walker, a minister at 38. He is currently a back bench member of Parliament and a member of the Conservative Party's overshadowed Health wing. Until Raw's book, at least , he could have nourished hopes of leading the Tories some day and becoming prime minister.

Raw notes that Walker, like Slater, sold his own stocks in one speculative company to investment clients relying on Slater Walker advice. Walker also his insurance business to Slater Walker for an estimated $555,000.

In office, Walker delivered strong speeches denouncing insider deals. He told Raw, "at no time did I perform any duty as deputy chairman, my relationship with (Slater Walker) was therefore never one of being involved in the detail of the company . . .

Slater's explainations appear in a book he has written which, by no coincidence, also appears on Thursday. It is named "Return to Go." after the game of Monopoly, which he enjoys, In it. Slater acknowledges that his technique of tipping stocks he had already bought "could be conflict of interest." But, he explains, "at that time stock exchange investment was relatively new to me."