Just about everybody must have had this fantasy: You survive a horrendous accident. Everybody assumes you're dead. So you slip away to the airport, hop aboard the next plane to some distant locale and start a whole new life.

Evidently a number of people lived out that very scenario two weeks ago in the confusion and turmoil following the fiery collision of two crowded commuter trains just outside London's Paddington Station. Some survivors of the accident, Scotland Yard says, walked away without a word to anyone and boarded international flights later that day.

Those disappearing passengers are a key reason police were so far off in estimating the number of casualties in the Oct. 5 disaster. Just after the crash, Scotland Yard said that the death toll would likely climb to 70, and possibly well over 100. But as time passed, and more passengers who were presumed dead turned up alive and well, the estimates fell sharply.

In a formal report to Parliament today, Deputy Prime Minister John Prescott, who is responsible for transportation, said the accident killed 30 people and injured about 250. These figures make the Paddington crash less than half as bad as the police reports initially suggested.

In fact, police say now, large numbers of the passengers believed to be dead turned up alive over the next few days. Some had simply returned to their normal routine, unaware that police assumed the worst about them. Others walked away from the crash and set off for foreign destinations without a word to anyone. Most of those phantom victims--police haven't said how many--evidently changed their minds and called home within a few days.

The problem of counting the dead was exacerbated, according to Deputy Police Superintendent Andy Trotter, by false reports from people claiming their spouses had been on one of the doomed trains. The callers evidently hoped to get a formal ruling that the spouse was dead, and then claim all the marital property. "We came across some very complicated relationships, and people not always being helpful," Trotter said.

Officially, 30 bodies have been recovered at the crash site, of which four have still not been identified. A few people who may have been on one of the trains remain unaccounted for, but police have gradually reduced the number of those presumed dead.

Paddington Station is probably best known to Americans because of the fictional teddy bear abandoned there. But to Londoners, it is a key transit hub; among other things, it's the downtown terminus for the express trains serving Heathrow Airport.

The crash was caused by an error called "signal passed at danger"--the railway equivalent of running a red light. The driver of the train that passed the red signal has not been blamed, however, because inspectors say the signal was obstructed and hard to see in the morning sun. Prescott told the House of Commons today that Paddington will not be reopened until 20 or more signals are made more visible. However, the government's safety watchdog agreed to reopen the station, which has been closed to all rail traffic since the crash, at midnight Wednesday if the offending signal was taken out of action and speed was reduced near Paddington, the Reuters news service reported.

Prescott said he would call an emergency meeting next week of all the companies now operating track and equipment in Britain's newly privatized rail industry. The session will focus on needed safety improvements in track, signaling, and driver training throughout the United Kingdom.