Arconic has marketed the flammable facades in Britain for years, even as it has adjusted its pitch elsewhere. In other European countries, Arconic’s sales materials explicitly instructed that “as soon as the building is higher than the firefighters’ ladders, it has to be conceived with an incombustible material.” An Arconic website for British customers said only that such use “depends on local building codes.”

For years, members of Parliament had written letters requesting new restrictions on cladding, especially as the same flammable facades were blamed for fires in Britain, France, the United Arab Emirates, Australia and elsewhere. Yet British authorities resisted new rules. A top building regulator explained to a coroner in 2013 that requiring only noncombustible exteriors in residential towers “limits your choice of materials quite significantly.”

Fire safety experts said the blaze at Grenfell Tower was a catastrophe that could have been avoided, if warnings had been heeded.

… But by 1998, regulators in the United States — where deaths from fires are historically more common than in Britain or Western Europe — began requiring real-world simulations to test any materials to be used in buildings taller than a firefighter’s two-story ladder. “The U.S. codes say you have to test your assembly exactly the way you install it in a building,” said Robert Solomon, an engineer at the National Fire Protection Association, which is funded in part by insurance companies and drafts model codes followed in the United States and around the world.

No aluminum cladding made with pure polyethylene — the type used at Grenfell Tower — has ever passed the test, experts in the United States say. The aluminum sandwiching always failed in the heat of a fire, exposing the flammable filling. And the air gap between the cladding and the insulation could act as a chimney, intensifying the fire and sucking flames up the side of a building. Attempts to install nonflammable barriers at vertical and horizontal intervals were ineffective in practice.

As a result, American building codes have effectively banned flammable cladding in high-rises for nearly two decades. The codes also require many additional safeguards, especially in new buildings or major renovations: automatic sprinkler systems, fire alarms, loudspeakers to provide emergency instructions, pressurized stairways designed to keep smoke out and multiple stairways or fire escapes.

And partly because of the influence of American architects, many territories around the world follow the American example. But not Britain.

… “If the cladding cannot resist the spread of flame across the surface, then it will vertically envelop the building,” Mr. Evans warned, in testimony that now seems prophetic. “In other words, the fire will spread to the outside of the building, and it will go vertically.” Many other fire safety experts would repeat those concerns in the following years.

But manufacturers argued against new tests or rules. Using fire-resistant materials was more expensive, a cost that industry advocates opposed.

“Any changes to the facade to satisfy a single requirement such as fire performance will impinge on all other aspects of the wall’s performance as well as its cost,” Stephen Ledbetter, the director of the Centre for Window and Cladding Technology, an industry group, wrote in testimony to Parliament.

“Fire resistant walls,” he added, “are not economically viable for the prevention of fire spread from floor to floor of a building,” and “we run the risk of using a test method because it exists, not because it delivers real benefits to building owners or users.” (In an interview last week, Mr. Ledbetter said his group had updated its position earlier this year to warn against the type of cladding used at Grenfell Tower.)

Business-friendly governments in Britain — first under Labour and then under the Conservatives — campaigned to pare back regulations. A 2005 law known as the Regulatory Reform (Fire Safety) Order ended a requirement for government inspectors to certify that buildings had met fire codes, and shifted instead to a system of self-policing. Governments adopted slogans calling for the elimination of at least one regulation for each new one that was imposed, and the authorities in charge of fire safety took this to heart.

“If you think more fire protection would be good for U.K. business, then you should be making the case to the business community, not the government,” Brian Martin, the top civil servant in charge of drafting building-safety guidelines, told an industry conference in 2011, quoting the fire minister then, Bob Neill. (“Should we be looking to regulate further? ‘No’ would be my answer,’” Mr. Neill added.)

Mr. Martin, a former surveyor for large-scale commercial projects like the Canary Wharf, told his audience to expect few new regulations because the prime minister at the time, David Cameron, wanted to greatly reduce the burden on industry, according to a report by the conference organizers.

Two years later, in 2013, a coroner questioned Mr. Martin about the application of building regulations in the case of another London fire, which killed six people and injured 15 others at a public housing complex called Lakanal House. Mr. Martin defended the existing regulations, including the lack of a requirement for meaningful fire resistance in the paneling on the outside of an apartment tower.

A questioner told him that the public might be “horrified” to learn that the rules permitted the use of paneling that could spread flames up the side of a building in as little as four-and-a-half minutes. “I can’t predict what the public would think,” Mr. Martin replied, “but that is the situation.”

Moving to a requirement that the exterior of a building be “noncombustible,” Mr. Martin said, “limits your choice of materials quite significantly.”

After the coroner’s report, a cross-party coalition of members of Parliament petitioned government ministers to reform the regulations, including adding automatic sprinklers and revisiting the standards for cladding. “Today’s buildings have a much higher content of readily available combustible material,” the group wrote in a letter sent in December 2015 that specifically cited the risk of chemicals in “cladding.”

“This fire hazard results in many fires because adequate recommendations to developers simply do not exist. There is little or no requirement to mitigate external fire spread,” added the letter, which was first reported last week by the BBC.

… But in Britain, still no changes were made. “The construction industry appears to be stronger and more powerful than the safety lobby,” said Ronnie King, a former fire chief who advises the parliamentary fire safety group. “Their voice is louder.”

… As recently as March, a tenant blogger, writing on behalf of what he called the Grenfell Action Group, predicted a “serious and catastrophic incident,” adding, “The phrase ‘an accident waiting to happen’ springs readily to mind.”

… For many tenants, an object of scorn was Grenfell Tower’s quasi-governmental owner, the Kensington and Chelsea Tenant Management Organization. It was created under legislation seeking to give public housing residents more say in running their buildings, and its board is made up of a mix of tenants, representatives of local government and independent directors. But Kensington and Chelsea is the largest tenant management organization in England, a sprawling anomaly supervising roughly 10,000 properties, more than 30 times the average for such entities. Tenants came to see it as just another landlord.

The organization had promised residents of Grenfell Tower that the renovation last year would improve both insulation and fire safety. Board minutes indicate that it worked closely with the London Fire Brigade throughout the process, and local firefighters attended a briefing afterward “where the contractor demonstrated the fire safety features.” During a board meeting last year, the organization even said it would “extend fire safety approach adopted at Grenfell Tower to all major works projects.”

… The cladding itself was produced by Arconic, an industry titan whose chief executive recently stepped down after an unusual public battle with an activist shareholder. Arconic sells a flammable polyethylene version of its Reynobond cladding and a more expensive, fire-resistant version.

In a brochure aimed at customers in other European countries, the company cautions that the polyethylene Reynobond should not be used in buildings taller than 10 meters, or about 33 feet, consistent with regulations in the United States and elsewhere. “Fire is a key issue when it comes to buildings,” the brochure explains. “Especially when it comes to facades and roofs, the fire can spread extremely rapidly.”

A diagram shows flames leaping up the side of a building. “As soon as the building is higher than the firefighters’ ladders, it has to be conceived with an incombustible material,” a caption says.

But the marketing materials on Arconic’s British website are opaque on the issue.

“Q: When do I need Fire Retardant (FR) versus Polyethylene (PR) Reynobond? The answer to this, in part, depends on local building codes. Please contact your Area Sales Manager for more information,” reads a question-and-answer section.