Management pundits have been heralding the arrival of the 'paperless office' for the last quarter century.

Ironic, then, that far from being swept aside by the hi-tech era, paper has continued to breed in offices like some sort of rodent immune to all poison.In fact, documentation is so crucial to the legal profession that lawyers spawned and continue to support their own method of exchanging paper.

Hayes Document Exchange -- which celebrates its 20th anniversary this month -- is a testament to the power of paper in the legal world.In law firms and chambers throughout the UK the system is now more simply known as the DX and the process of sending documents as 'DXing'.The figures speak for themselves.

Every night the DX carries some 750,000 pieces of mail for its 27,500 subscribers, about 14,000 of whom are in the wider 'legal community'.

According to new HDX managing director Robert Morgan, that nightly load is equivalent to 1% of the Royal Mail's daily volume.The added value for DX customers -- or members as they are politely referred to at head office in Iver, Buckinghamshire -- is the virtual guarantee that mail will be delivered before nine o'clock the next morning.

DX manages this feat by operating a network of 35 sorting centres and 2800 drop-off points around the country, which are then linked by about 220 courier routes.

Technically speaking, members are not meant to send packages heavier than two kilos through the DX but exceptions can be made, especially at Christmas when crates of whisky and fancy dress outfits have been know to pass through the sorting centres.

Indeed, one barrister stretched DX managers' tolerance to the limits when he sent a lawn mower through the system.Clinching success for DX is its ability to offer the service at a highly competitive price.

While overnight courier firms will also deliver early on a following morning, they are comparatively more expensive.

DX charges a one-off joining fee of £200 and then an annual subscription based on how much mail is sent.

Roughly speaking, a firm could start on about £350 annually.'It is a real British success story,' says Mr Morgan.

And it is difficult to argue.

Last year, the Hayes group -- which bought the DX from its founder and now chairman, Henry Seymour, in 1980 -- made a £110 million profit on a turnover of some £870 million.

Profits were up by 16% over the previous year.Mr Seymour got the germ of the DX idea some 20 years ago, following a trip to Australia.

Back in England, he linked up with Australian solicitor Pauline Lisle-Smith who had experience of the Sydney DX.

In 1975, British industry was beset by industrial unrest, with the Royal Mail experiencing a series of one-day and longer strikes.

But perhaps the main boost to Mr Seymour's new venture was a six pence hike in postal charges.

Mr Seymour first set up the London Document Bureau which consisted of two exchanges.

Both were in the City; one serviced the insurance sector and the other, based in Chancery Lane, catered for the legal profession.A fter being bought up by Hayes, the name was changed to the British Document Exchange -- or BritDoc -- and the operation began to expand into the provinces.

It drew up reciprocal arrangements with exchanges in the Midlands and in Scotland, and by the early 1980s the group could provide a pre-9am delivery service around the country.

By the early 1990s the DX had taken over the other two exchanges, and just this year it had a new name and its corporate image revamped.Although law firms and chambers easily form the DX's core business, there are other customers; financial service companies, building societies, local government authorities and utility companies have all become DX converts over recent years.There are also non-lawyer clients in the legal community, such as courts and police forces.

Indeed, some barristers are so taken with the service that they have asked for their own delivery boxes at court as well as in chambers.But, according to Mr Morgan, the typical DX member is a small to medium-sized provincial law firm.

Somewhat surprisingly, DX directors reckon that they get more business from firms in Leeds and Birmingham than they do from the top ten commercial players in the City.

They have also been surprised to see the volume of legal document traffic between England and Scotland.

Says Mr Morgan: 'I had been told that Scottish lawyers do not correspond with English lawyers but we move about 2.5 tonnes of mail a night from the Scottish legal profession south to England and we probably do about half that again going from the English profession north to Scotland.'In fact, Scotland is the final piece in the jigsaw to be added.

From the middle of November, even the farthest reaches of Aberdeenshire will receive deliveries by 9am, says Mr Morgan, himself a Scot.

To accomplish this, DX is going to lay on its own aircraft for the first time.One of the most striking elements of the DX phenomenon, says Mr Morgan, is the high level of customer loyalty.

The average DX client has been with the service for about ten years.

During the last 18 months Mr Morgan's team has been tracking customer satisfaction.

He maintains that the service scores highly on key issues such as whether the customers received their mail on time, whether it was the mail they expected to get, and was it in one piece? Mr Morgan says an example of DX staff expertise is their ability to deliver some pieces of poorly addressed mail by simply recognising the sender's handwriting.Where DX needs to improve, by Mr Morgan's own admission, is in the area of customer service.

'Do we get back to people who have queries on time and with the right level of information? Do we resolve queries to the customer's expectation?' The company has just beefed up its customer service team by 35 in an attempt to pick up its rating in that field.Mr Morgan is also adamant that the firm has not been tempted to become complacent because of its success.

A research and development team is working on new services to bolt on to the core mail delivery function.

One possibility is to go into law firms to sort out their internal documentation flow.

Another is a possible document storage facility.But DX, says Mr Morgan, will not forget its roots.

It is looking to set up an overnight delivery service to law firms throughout Europe, starting with Belgium and France.