Swan-song for the big red bus: London's pride: The Routemaster, beautiful, efficient and simple to maintain, is 40 years old this week. But age and galloping privatisation mean its days are numbered. Jonathan Glancey reports

The Routemaster, still the world's finest double-deck bus, is 40 years old. It is one of the few surviving links with those unsung men and women who once dreamed of a public transport system that was efficient, integrated and beautiful: a work of civic art shaped equally for the toff in Sloane Street, the char working the City Road and everyone else from Tooting to Totteridge.

It is the last of a line of buses custom-built for the capital which began with the B-Type of 1904. This was the first proper, standard-issue red London double-decker and the one that went to war in France in 1914.

The Routemaster was designed by a team of engineers and stylists in the days before superstore culture overwhelmed us, passengers became 'customers' and London Transport was still the stuff of spiffing books with titles such as Marvels of the Modern World.

Decade by decade, the boffins and craftsmen of London Transport's Chiswick Works strived to build a better, more efficient and more elegant double-deck bus. The Routemaster was built to replace London's extensive electric trolleybus fleet (the last ran in 1962). It was also designed to fit in with the extraordinarily consistent look of London Transport's existing bus fleet, as well as its Underground stations and trains. The shape of the bus - a thing of subtle curves, despite its inevitable bulk - was styled to enhance the look of the streets it served.

The prototype was developed over several years before LT engineers were convinced that they had the best possible bus for London. It was to be simple to maintain, cheap to run and enduring. It was to be up-to-the-minute but not gimmicky. It was therefore built as a sophisticated kit-of-parts that could be taken apart, renewed and put together again as quickly as the automated Aldenham bus maintenance works near Elstree Studios would allow. (Aldenham Works was the now defunct centralised bus overhaul depot that co-starred in Summer Holiday; Cliff Richard, the star, drove an RTL, an older design, but, doubtless, the new Routemasters were too busy.)

For drivers and mechanics alike, the Routemaster was a big improvement on existing London Transport buses. It boasted automatic transmission, power steering, a commanding driving position, powerful brakes and, for a bus, supple suspension. It still outperforms every ill-conceived double-deck shoebox that has tried to oust it over the past 25 years. It is a doddle to drive, once you get used to its length and width, and it handles the road with remarkable finesse.

For passengers, it remains the most practical London bus. It is easy to get on and off in crowded streets, it goes faster (because it has a conductor to collect fares) and it does not rattle and vibrate like a rear-engined bus. It also has lovely details such as the minutely engineered windows that wind down at the turn of a crank, rather than modern sliding windows that are likely to stick either open or shut.

Until fairly recently, Routemasters were turned out as smartly as guardsmen on point duty outside Buckingham Palace in their London-wide uniform of scarlet, black and gold. Every bus displayed the same noble Johnston typeface (dating from 1916, a peerless display Roman face, since bastardised by what remains of London Transport) front and back.

Inside and 'on top', the decks were fitted out in leathercloth, a tartan moquette designed by Douglas Scott, primrose paint (to hide nicotine stains) and subtle lighting. No garish fluorescence then to highlight passengers' pimples. Sadly, the 500 Routemasters that have been refurbished for a further 10 years' service have been refitted with the tackiest interiors imaginable: grey walls that show the dirt, seat fabrics better suited to a building society headquarters and a palette of clashing colours vomited up from an artistic void.

By the end of this year, London's bus companies will have been completely privatised. According to London Transport, which remains the regulatory body for the capital's buses and Underground trains, Routemasters, like all London buses, will stay red. This ruling does not apply retrospectively to those companies which have chosen to paint London buses in such visually challenging colours as rhubarb and custard or drab green and drabber grey. Yet, whatever colours they have painted their buses, the privateers will hang on to their Routemasters for as long as possible. A replacement is unlikely because the privatised companies do not have the purchasing power to commission a custom-built bus.

The Routemaster should have been replaced by now. It is a good bus, still the best there is, but by the Eighties a new and improved London double-decker should have taken its place. A new bus might well have retained the open platform, conductor and lovers' seat upstairs at the back that make the Routemaster and its predecessors so enjoyable to ride.

It would have been a stylish vehicle with an interior styled by the best designers of our day. But such a bus must remain a pipe dream. The Routemaster is truly the end of the London bus as Londoners and visitors to the capital have known it for the past 80 years. Passengers will rue the day, while 'customers' will, presumably, be oblivious to the decline of the London bus from work of kinetic civic art to parts-bin cattle-truck.

Routemaster: 40th anniversary celebration: Saturday, at Covent Garden Piazza and Royal Victoria Dock. Over 100 RMs on display. Regular RM service between Covent Garden and Royal Victoria Dock from 9.30am (first bus from Covent Garden) until 5.45pm (last bus from Royal Victoria Dock). Day ticket pounds 7 (adults), pounds 5 children and concessions (family ticket: pounds 20) includes visit to LT Museum and use of RM bus service all day. David Shepherd will sign copies of his new print of a Routemaster from 11am at Covent Garden Piazza .

DESIGN FACTS

Designed by London Transport engineers (Chiswick Works) with Douglas Scott (interior and exterior styling and interior decor)

Built by Chiswick Works and AEC (Southall)

Prototype: RM1 1954

Production: RM 1958-1965

RML: 1960, 1964-67 (lengthened version)

Other Variants: RMC (Routemaster Coach for Green Line services)

RCL (Routemaster Coach, lengthened version)

RMF 1962 (Front entrance, prototype)

FRM 1965 (Front entrance, rear engine, prototype)

QRM 1970s (drawing board RM replacement; not built)

Total built for London Transport: 2,760

BEA (London Airport coach service) and Northern General (Gateshead) were the only other companies to buy Routemasters from new. Today second hand Routemasters run in many towns and cities, notably Glasgow and Manchester. They can be bought and used as private vehicles. The artist David Shepherd is one proud owner.

One single deck Routemaster exists. It was rebuilt by LT from a double-decker venturing under a low bridge.

Technical Data

Dimensions:

Length: 27ft 6in or 30-ft

Width: 8ft

Height: 14ft 6in

Weight: 7ton 5cwt (7ton 15cwt RML)

Seats: 64-72

Bodywork:

Chassisless construction

All aluminium body (detachable panels for easy repair)

Engine:

AEC 9.6-litre or 11.3-litre 6-cylinder, in-line, direct-

injection diesel 115bhp 1,800rpm

(Refurbished Routemasters have been fitted with either a Cummins 8.3-litre or Iveco direct-injection diesel)

Transmission: 4-speed automatic with manual override

Suspension: All independent, spring coils. Some late

production buses are fitted with air-suspension at rear

Performance (RM)

Max Speed: 47mph

0-40mph: 29 secs

Fuel Consumption:

Urban cycle: 9mpg

(Photograph omitted)