Borrowing sensibly is Symes's only option for expansion. But so determined is Mars to remain free from the constraints of the City that it has enshrined its position in the company principles. "Private ownership is a deliberate choice," the text states. "Many other companies began as Mars did, but ... to extend their growth, they exchanged a portion of their freedom." In contrast, Mars believes that profit is the engine for "growth and prosperity".
It is a high-minded position that both Mars and John Crane can sustain. After all, they are big enough ventures to fund their development out of group profits. But the common thread is a determination to retain control of the business, letting neither the City nor the bank dictate policy. This independence from other imperatives is crucial to the longevity of Britain's manufacturing base.
Yet the success of individual manufacturers, heartening though it is, does not represent a total picture of the course that industry has taken in the South-east. Neville White, external affairs manager at Slough Estates, recently noted in an article for the Slough Observer that 50-odd years ago there were some 250 industrial firms on the estate, employing 28,000 workers at an average wage of 52p a week. "Most of the industry was devoted to manufacturing, using heavy engineering techniques, and was highly labour intensive."
Today the situation is very different. In "Long Lease", a newly published history of Slough Estates, Michael Cassell sums up the change: "The days when the estate was crammed with engineering and automative companies have long since gone; the age of the service industry has arrived and nowhere can it be more readily identified than at Slough, where oily workshops have given way to squeaky-clean distribution centres and computer complexes."
Sir Nigel Mobbs, the current chairman and chief executive of Slough Estates, estimates that when he first joined the family business in the early 1960s, a good 50% of the trading estate constituted heavy industry. Nowadays manufacturing is down to 25 to 30% at most.
Sir Nigel attributes the change to a number of factors, including the way in which space has been redefined. "In the 1920s and '30s", he points out, "the works manager would have his desk in a cubicle in the factory." These days he gets a seat in the office. Moreover, "more and more manufacturing is being concentrated into smaller areas because the actual processes are becoming more concentrated". But the biggest shift which Sir Nigel identifies is that "from the business headquartered in Slough to those which are branches of bigger groups and in the process become support industries".
In some cases the transition is a measure of the manufacturer's success - Johnson and Johnson relocated to nearby Maidenhead because it could afford to buy premises which it had once been able only to lease - while escalating land and labour costs have driven a number of firms further north. Others have remained on the estate but changed hands - Bells Asbestos became Bestobell, Crane Packing became John Crane. The net impact of this shift in ownership is often to remove control of resources from the community where they are generated.
For Sir Nigel, indeed, it must be a particularly cruel irony that Slough Estates, which for so long has helped to foster that community, is now itself in trouble. Though many of the infants suckled on the estate may be thriving, their wet nurse has just posted pre-tax profits of £22.6 million, down 72% on the previous year.
Nevertheless, in many respects Slough remains a reasonably accurate gauge of Britain's manufacturing industry. We can hardly compete with the cheap labour available in a tiger economy, but, though complacency would be foolish, there is enough evidence to suggest that British manufacturers can excel. The news may not be all good, but a "slough of despond" is unnecessary.