And yet this is no corner-shop operation. Its 45,000 employees are spread around the globe - contributing to total turnover that last year exceeded pounds 300m from locations as far apart as Canada, Malaysia, France and the UK. The company is involved in activities as varied as security and facilities management in addition to the window cleaning with which it started.
Nevertheless, the current management is determined to retain the family- business attitudes that have characterised the company since its establishment in 1900 by Frederick Goodliffe. With the small shipping firm he ran with his brother put out of business by the Boer war, he found work as a canvasser for a London window-cleaning company before setting up on his own.
The New Century Window and General Cleaning Company started with a ladder, a pail, a small lorry and one man part-time. Its address was a sweetshop and the equipment was kept in the yard of a nearby pub, but the fledgling company prospered as the century progressed - struggling through the First World War before resuming the growth path that has continued to this day.
Various relatives began to enter the business and a 1930 venture into office cleaning sowed the seeds of the group's current name. Since then, the group has either established or acquired businesses in such areas as aviation and airport services, feminine hygiene, laundries and mechanical and electrical engineering as well as cleaning and security.
Chris Cracknell, the current managing director and a member of the fourth generation of the family to be involved in the business, sees all these areas as "platform services that we can build on". But he also insists that such expansion is always driven by customer needs. The focus is to provide the "right environment" for customers to produce the widgets or whatever products or services are core to their business, he adds.
Mr Cracknell, while clearly proud that he and his colleagues have the chance to pass something down through the generations, stresses that relatives do not have the right to rise through the company. They are given opportunities, he says, adding that - while there are about 20 members of the family working in the business - there also many non-family members in prominent positions.
Accordingly, the business is still owned by about 154 shareholders. Though it reported pre-tax profits last year of pounds 13.2m, he points out that it can take the long view and not worry about satisfying City analysts' demands for constantly rising rates of growth.
Mr Cracknell confirms that his company attracts the interest of would- be buyers. But he cannot see himself being tempted. Moreover, Mr Cracknell believes that the style of the business makes people want to stay. Though the corporate headquarters is now near Croydon, Surrey, very few people work there, and much of the decision-making is devolved to the individual businesses.
However, that does not mean that they are left to fend for themselves. While some people might feel having operations in such places as Thailand and Malaysia brings unreasonable exposure to "Asian flu", Mr Cracknell, who has been MD for two-and-a-half years, sees plenty of future opportunities in the area. Moreover, he points out that the region provided plenty of growth when the UK market was less strong.
"Our risk is to some degree spread either by division or geography," he explains. "There's a need for us all to work together. We're playing a team game," he says.
OCS might qualify for inclusion in the KITE/Independent 100 survey of fastest-growing companies that was launched last weekend by The Independent on Sunday in conjunction with BDO Stoy Hayward, the accountancy firm specialising in advising growing businesses.
n If you think your firm qualifies for inclusion in the league based on annual sales growth over five years, then send for an application form to Philip Rego, KITE/Independent 100, Willoughby House, 439 Richmond Road, East Twickenham, Middlesex TW1 2HA.Reuse content