IT HAS long seemed to me that James Baker has enjoyed the unfair advantage of not being Donald Regan. Now that Mr Baker has landed the bets of Wall Street, by tiptoeing out of the US Treasury and into the driving seat of George Bush's campaign, he will have to manage without it. In Ronald Reagan's first term as presi- dent, Mr Baker was chief of staff and Mr Regan was Secretary of the Treasury. Those were the years when the Treasury, in the name of 'supply-side economics', set off on the single-minded course of borrow- ing which has given the US its intractable deficits on its budget and on its balance of payments, and established it as the world's biggest debtor. They were also the years of the Teflon presidency, when nothing unde- sirable stuck to the President — the non- stick surface being laid down by the smooth operations of his chief of staff. Mr Reagan was re-elected in a canter, and soon afterwards Mr Baker and Mr Regan swapped jobs. Mr Baker resumed diploma- tic relations with his fellow finance minis- ters, negotiated the dollar down from its unsustainable heights, restored life to the rusty industries which the exchange rate had choked, and settled down to launch a pre-election boom for Mr Bush's benefit. Mr Regan, less than diplomatic in the White House as elsewhere, soon let the Teflon coating get scratched, by a sequ- ence of scandals and quarrels which finally cost him his place and could yet cost Mr Bush the election. (He went on to tell us how the Emperor Ronald was governed by the Empress Nancy, and how she was governed by the stars.) Mr Baker, I see, says that his campaign's watchwords will be peace and prosperity. He must cross his fingers as the anniversary of the October crash approaches. Perhaps for safety's sake he could arrange for Mr Regan to come out for Michael Dukakis.