It has been driven by many other things: for example, the high liquidity of the savings institutions and pension funds, expectations of continued good earnings by large companies, by the fall in inflationary expectations and hence in bond yields, or simply the fact that looking round the world there are not many other attractive places to stick the money.I would accept all that, but still argue that underpinning Wall Street is a sense of general self-confidence, of which confidence in American exceptionalism is an important constituent part. So you can have corporate exceptionalism co-existing alongside quite muted productivity growth in the economy as a whole.Looking ahead, there are reasons to expect rather slower growth in the US economy this year – it grew at 4 per cent in 1997 and clearly cannot keep that sort of breathless rush going for ever. As anyone who visits the US regularly will have noticed, the quality of service continues to improve – but it is very hard to pin this down in the statistics.Nevertheless, it is clearly much harder to increase productivity in service industries than in manufacturing, which is a problem since only about 18 per cent of US GDP is now generated by manufacturing. It is easy to improve productivity if you are coming from behind, but extremely difficult if you are already far ahead.The other point is less impressive. If you look at manufacturing things are terrific, and when we think of large American companies we usually think of manufacturers.

If you look at the whole economy, the performance is less wonderful. This is the flip side of the amazing ability of the US economy to create jobs: in the service sectors, productivity has not been rising fast, for companies have been tending to meet additional demand not by improving productivity but by taking on more people.As with all figures, you should take this with a pinch of salt. I suspect that these general productivity numbers fail to take into account improvements in the quality of service that has taken place in the US. It ran at between 2 per cent and 6 per cent a year through most of the 1980s, remained positive through the early 1990s recession, and then pulled away right through the ensuing boom.

It is an astonishing performance, all the more so since productivity in US manufacturing was already higher than anywhere else in the world at the start of the period. Anyone who works with the best large US corporations will be aware of the quality of management, the attention to detail, and sheer hard work of the people there. But to say that big US companies are very good and are becoming better is not just an impressionistic judgement: you can see it in the figures Have a look at the graph on the left. It shows what has been happening to US productivity over the last 25 years, productivity both in manufacturing and for the non-farm business economy as a whole.
A couple of obvious points emerge. IS US business really so exceptional? It is a crucial question because so much of the enthusiasm on Wall Street is founded on the assumption that something special has happened to American companies – that they have somehow made a step change in their efficiency, and that this superior performance will enable the economy to race onwards. One is that since the early 1980s recession manufacturing productivity growth has put in an extremely solid performance.

A brief visit to the States last week has convinced me that something special has indeed been taking place in the US – but that it is not quite as special as Wall Street seems to think. However, it could be something of a “spring ramp”.Mr Blackbourn, famed for the response to his 3.1 per cent shareholding in Tadpole Technology, did have 1 per cent but has since sold most of his shares.Honeysuckle, the fashion group, fell 3p to 15.5p after disclosing it was in refinancing talks.Speculative buying pushed Cox Insurance 23p higher to 328p A year ago the shares were 149.5p.. This wiped pounds 1bn off the value of its shares.Most analysts expect Thursday’s results to show pre-tax profits of a shade over the pounds 1bn mark compared with pounds 1.3bn last time.But one said: “With BTR’s record you never take anything for granted.”Most City forecasters expect a very slight deterioration in 1998 results over 1997 figures. BTR watchers say the company’s management will only be treated more favourably when it not only completes its sales programme but also shows that it can run a going concern at a premium.Outlook, page 21. PERKINS FOODS boosted its shares yesterday with the sale of its fresh produce business and plans to return pounds 45.4m to investors.

The company said it had got an attractive price for the business, which it has agreed to sell to Dutch produce marketing group Greenery International for pounds 123.6m. Perkins’ shares rose by more than 10 per cent, ending at 138.5p, up 13p. The company said the deal would enable it to develop its faster-growing chilled and frozen food divisions around Europe, where it already supplies 15 of the top supermarket groups, including Tesco and J Sainsbury.
Ian Blackburn, the deputy chief executive, said Perkins was not only getting a very good price for the division, regarded historically as the lower quality one, but would have ample resources to invest in the remaining two, even after giving money back to investors.”We are a smaller business but should be much faster growing,” said Mr Blackburn, who will take over from the current chief executive Howard Phillips when he retires at the annual meeting. Merger talk lifted Hepworth 12.5p to 237.5p and rumoured partner Marley gained a further 2p to 112.5p.Next, following the signalled departure of Lord Wolfson of Sunningdale as chairman, fell 36p to 792.5p. The recent round of corporate action as well as rumours of more to come, a firm New York opening and the feeling interest rates will be pegged again this week were other influences.Optimism was encouraged by two significant Footsie upgrades. SG Securities raised its year-end target from 5,350 to 6,000 and Panmure Gordon went from 6,000 to 6,600.Footsie’s volatility, however, was underlined by a late 25.4 fall, leaving the index 53.3 up at 5,820.6.WPP, the advertising agency, illustrated the way order-driven trading was continuing to heighten the uncertainty over closing Footsie prices.Dealings in the shares were suspended as the market closed with the buying price at 310p against 304p on the sell side.