Thirty-two candles were lit at 8.08am on Saturday in St Helens church, just south of the rail tracks at Ladbroke Grove, west London. One candle each for the 31 people who died in one of Britain’s worst rail disasters, exactly 20 years ago; another for the surviving passengers, more than 250 of whom were injured. Two trains collided in the morning rush-hour at a combined speed of 130mph. In the wreckage, fires broke out, completely incinerating carriage H of the incoming commuter train.

Families and survivors as well as first responders later observed a minute of silence at a memorial close to the crash site and trains were halted. Representatives of the London fire brigade and London ambulance service, as well as the Metropolitan police commissioner, Cressida Dick, laid wreaths.

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The Ladbroke Grove, or Paddington, disaster was the most horrific of four train crashes in the early aftermath of privatisation: horrific in the scale and nature of its casualties, and for the failures behind it. Among the factors identified were insufficient driver training; a lack of automatic protection systems; and a crucial railway signal – number SN109 – that was a known risk. In the preceding six years, seven other train drivers had, like the driver of the Thames train, failed to see the red light and stop, yet no action had been taken.

Only two years earlier, seven people had died two miles west on the same stretch of line in a train crash at Southall. Calls for train protection systems that could have averted both disasters were ignored.

Looking back now, under Britain’s redoubled rail safety regime established by the Cullen inquiry, it seems unthinkable. Only one passenger has died in a train crash in the last 14 years, in 2007 when a Virgin Pendolino derailed at Grayrigg.

Yet safety is far from perfect. Three rail workers have been killed by trains in the last 12 months. Minor accidents on the mainline have risen after five years of improvement, according to the Office of Rail and Road. The Rail Safety and Standards Board – one of two bodies created in the aftermath of Ladbroke Grove – warned that 41 trains passed red signals this July, more than in any single calendar month since October 2007.

In August, the brakes failed on a new Caledonian Sleeper train, which came to a halt 600 metres after it should have stopped at Edinburgh Waverley – an incident that could have easily been a major disaster, according to accident investigators.

Such factors are prompting concern, especially as the government prepares, with the Williams review, to embark on the biggest overhaul of the railway’s structures since the creation of Railtrack in 1994.

Facebook Twitter Pinterest The scene after the Potters Bar crash in 2002. Photograph: Michael Stephens/PA

Railtrack, the privatised company managing the infrastructure, became a byword for disaster. After Southall and Ladbroke Grove, its ignominy compounded when track failures caused the Hatfield and Potters Bar crashes in 2000 and 2002.

The political decisions that led there, and the human cost that ensued, were dramatised by Sir David Hare in The Permanent Way, written in 2003 and currently in an acclaimed revival at the Vaults theatre under London Waterloo. It is formed from verbatim accounts from survivors, bereaved relatives and rail professionals – as well as relatively insouciant government officials behind privatisation, who threw up the pieces to see where they would fall. “The people who dreamt up the scheme and saw it through – they really did just walk away,” Hare now says. “Their lack of responsibility was shocking.”

Hare says the maligned Railtrack chair, Gerald Corbett, “felt the greatest sense of responsibility and regret” for the disasters. He offers a contrast with the reaction of a train operator who flew to the scene of the Hatfield crash, to be told the track was faulty: “He said: ‘Thank God it’s not us’. Responsibility is delegated … the minute you separate it, everyone is blaming everyone else. Safety is harder to administer because it’s harder to know where the buck stops.”

Rail’s structures dreamed up by the privatisation gurus of the 1990s – are again under scrutiny.

Hare does not blame privatisation per se for the crashes. He says: “The reason for each one was subtly different – but the priorities had changed. The engineers had a feeling that managers taking over meant safety was overlooked. There was an imbalance: the engineers were thought to be hopelessly old-fashioned, but of course they knew a lot about track and signalling.”

Facebook Twitter Pinterest William Cullen chaired the Ladbroke Grove rail crash inquiry. He recommended setting up the Rail Accident Investigation Branch. Photograph: Peter J Jordan/PA

Christian Wolmar, the rail historian, says: “There was a dislike of engineers in Railtrack days, the ‘wrong culture’ – and they are now talking about it again.”

He notes that the chair of the government-commissioned review, the former British Airways boss Keith Williams, earlier this year said: “You don’t create a customer-focused railway by putting engineers in charge.”

Whatever system Williams opts for, he has suggested he shares an emerging consensus that franchising, and the fragmentation of the railway – the separation of track and train – do not work. A new, arms-length body overseeing operations and infrastructure is likely.

That prompts a note of caution from Simon French, the chief inspector of the Rail Accident Investigation Branch (RAIB): “I do have concerns about organisational change, and I believe every senior manager should share them. Change may be a good thing – but it needs to be carried out with great care to ensure you don’t have the unintended consequence of reducing safety.”

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The Ladbroke Grove train crash and Lord Cullen’s life-saving work | Letter Read more

The RAIB was set up on the recommendation of William Cullen, who led the inquiry into the Ladbroke Grove crash. As an independent, “no-blame” body, its job is to establish facts and draw lessons on safety; witness statements should not be shared with law enforcement agencies. Crash survivors, as well as French, credit Lord Cullen’s vision for transforming rail safety. Chris Goodall, injured at Ladbroke Grove, now says: “His fair-minded rigour has probably saved hundreds of lives across the UK.”

The Department for Transport said it was working with the safety bodies to ensure any reforms maintain the UK’s record. The rail minister, Chris Heaton-Harris, said: “We are all duty-bound to maintain the highest standards, ensuring such tragedies do not happen again.”

But Wolmar says: “I worry that complacency comes in, just for the sheer fact we haven’t had an accident for so long. The collective memory can forget that a major disaster is just a series of unlucky mistakes away.”