Some 430 tenants currently occupy the trading estate's 7.5 million sq ft of developed space. Much the biggest is Mars, with nearly a million sq ft of factory and offices. It is a far cry from August 1932, when a brash young American called Forrest Mars first made the chocolate bar which immortalised him. A quarrel with his father had brought Mars to Britain, where, with a few thousand pounds of capital and 12 staff, he began to tap into the British sweet tooth. Now his confectionery business employs 2,300 people.
Corporate affairs manager Locksley Ryan attributes the Mars success story to its egalitarian work practices - even the MD must clock in - and to the "five principles" which supply its philosophy: quality, responsibility, mutuality, efficiency and freedom, for which read freedom from the City. However, Mars-speak aside, Ryan puts his finger on a feature common to manufacturers based in Slough. "In effect we're a global, not a national, company," he explains. Mars is structured on "informal networks" rather than clear divisions between parent and subsidiary. Ryan proudly adds: "Slough is the chocolate capital of Europe." In short, Mars has looked beyond the domestic market to foreign mouths.
Of course, Slough is conveniently located for easy international access, but it is a point which gets reiterated by all. Symes, another rebel who told his father to "stuff your good old family business up your family backside", notes: "We've had to go further for our work because many of our customers have moved out of the Thames Valley."
Sitting behind the enormous desk which he inherited from his father-in-law, Symes sports a check jacket and cigar. He could easily pass for a 19th century squire. He is anything but parochial in outlook, however, and Metal Colours has actively been seeking to increase its share of foreign business. "We're a bit insular," Symes concludes. "But the market is too small. England is just a little market town. We must look to the whole world."
David Crofts, European managing director of John Crane, makes the point even more forcefully. Crane Packing, as the company was formerly known, can trace its ancestry to 1923, when another young Yankee came to Slough. In 1987 it was bought by TI Group and along with a change of ownership went a change of name. John Crane International, as it is now called, is thriving "because it has been imaginative in developing its distribution channels outside the UK". It is, Crofts adds, a "classic British management problem" to rely on "tied markets" such as those which the Empire and Commonwealth once offered.
But looking abroad for customers is not all that characterises these companies; they are also prepared to learn from the best manufacturing practices adopted elsewhere. At John Crane what Crofts calls "Japanese-style cellular manufacturing" and JIT (just-in-time) are well established, though colleague Bob Gibbon suggests that such innovations are more often American in origin - he cites Henry Ford as an instance. Certainly its American antecedents account for a considerable part of the Mars style, where even the MD sits in a vast open-plan office.
Both firms emphasise the degree to which responsibility is vested in their staff and both lay claim to an enlightened employment philosophy. The quiet-spoken Crofts talks of nurturing a "family feeling", while his rugger-playing fellow managing director is "Bob" to everyone from the doorman to the operatives on the factory floor. Similarly, Ryan speaks of Mars as an "extended family", with "associates" rather than employees. No terminological ploy can substitute an emotional for an economic relationship, but what does come out very clearly is that both companies have a commitment to paying, training and ultimately retaining their staff.
At a much less sophisticated level the same is true of Metal Colours. Many of the men on the factory floor have worked for the company for 10 years or more. But though Symes is keen to promote good relations with his staff, he makes another vital point - that it is equally important to maintain good relations with the bank.
A practical man who compares running his business to managing a household budget, Symes sends his quarterly accounts to the bank and invites the bank manager to attend board meetings. This openness has paid dividends, he believes, in enabling him to pursue his ambitions for modernising and purchasing new plant.
Symes wants "to see a much closer relationship between the money lenders and industry". But he also argues that short-termism is not just the fault of the City; "It really comes down to you and me," he points out. The individual shareholder wants a quick return as much as the institutional investor does, and "it's even more difficult to disappoint the little old pensioner down the road".