Almost half a million rail passengers face the biggest change in their daily train journeys since electricity replaced steam.

South West Trains (SWT) announced a completely new timetable for the first time in nearly 40 years. For many commuters to London, this will mean longer journeys and fewer trains stopping at their stations. But busier stations will get more frequent services.

The operator, which carries 400,000 people per day on 1,635 local and long distance services to Waterloo, said its current timetable cannot cope with the large increase in passengers.

Last year SWT handled 143 million passenger journeys, a whopping 40 million more than eight years ago. The masses of people take so long to get on and off at some stations that the current timetable is ruined.

The schedule was drawn up with electrification in 1967. Since then SWT made only slight changes about twice a year. "Rather than tinker around the edges of the timetable, we decided to go back to the drawing board and start from scratch," a spokeswoman said.

The new timetable is based on better train performance and passenger demand today. Departure times were standardised to help passengers remember them.

More trains will call at busy commuter centres like Surbiton and Walton-on-Thames, as well as at all stations on the Hounslow loop. But services on the quieter Alton-line in Hampshire will be less regular.

Trains will stop for longer at busy stations, instead of trying to stick to "unrealistic loading times".

The changes will take effect on December 12.

But the Rail Passengers' Committee of Southern England, which has negotiated with SWT about the changes since April, is "very unhappy" with the new train times.

Mr Tim Nicholson, chair, said: "Too many passengers will be disadvantaged by the details of the time table." He was "especially concerned" about longer journey times.

Trains to and from Alton will stop at suburban stations in London, taking an extra 5 to 10 minutes to reach Waterloo.

To meet performance targets, services from Salisbury, Wiltshire, will have a built-in time buffer on the congested tracks between Claphan Junction and Waterloo. "They are adding time just so that they are not late," Mr Nicholson said.

The new timetable will be available on the SWT website by the end of the month and at stations by mid-November.

More trains
Stations with a more frequent service include: Queenstown Road Battersea; Wandsworth Town; Barnes Bridge; Chiswick; Kew Bridge; Brentford; Syon Lane; Isleworth; Hounslow; Earlsfield; Motspur Park; Stoneleigh; Ewell West; Surbiton; Weybridge; Walton-on-Thames; Farnborough; Fleet; Frimley; Camberley; Bagshot; Wraysbury; Sunnymeads.

Fewer trains
Trains will call less frequently at: Worplesdon; Witley; Liphook; Liss; Rowlands Castle; Aldershot; Farnham; Bentley; Alton; Winchfield; Hook; Tisbury.