The fire was unusual because fire spread rapidly and downwards
Southwark Council knew a south London tower block where six people died was a fire risk, a BBC London investigation has discovered.
In 2000 the council surveyed 200 tower blocks, identifying 13 that "may pose a fire risk or risk of a fire spread".
Four of the 13 buildings were then demolished - but Lakanal House in Camberwell, gutted by fire on 3 July, was allowed to remain inhabited.
Southwark Council said it carried out works in 2007 to improve fire safety.
BBC London has obtained the report into the safety of Southwark's tower blocks that was commissioned in 2000 by a parliamentary committee investigating a fire at a building in Scotland.
The council's report rated all five buildings on the Sceaux Gardens estate, including Lakanal House, as a medium fire risk - "where elements of construction may pose a fire risk, or a risk of fire spread."
We do not believe it should take a serious fire in which many people are killed before reasonable steps are taken towards minimising risks
"I spoke to Dayana the morning she lost her life - I had no idea in a couple of hours she would be dead."
After the 2000 report, Southwark Council did not act for seven years.
But in 2007 they replaced some window frames and wall panels in an attempt to improve safety.
BBC London's questions about how many windows and panels were replaced and which materials were used have not been answered.
The council also refused to confirm whether a new fire assessment was done after the refurbishment.
Ms Trindade said her replacement window frames were plastic, not non-flammable aluminium.
Architect Sam Webb, an expert in the safety of post-war social housing, raised the possibility that melting plastic windows helped spread the fire downwards.
After visiting the scene on 6 July, he said: "All the facades and window frames were replaced with flammable uPVC which melts in fire, releasing toxic fumes.
"I am not sure how that was ever allowed on such a high block and it was undoubtedly a major cause of the fire spread."
But Philip Law, of the British Plastics Federation, disputed the claim. He said: "PVC does not melt or drip in fires.
"It develops a carbonaceous char which inhibits further spread of the fire."
Bob Wilkinson, a firefighter with 20 years experience in London, said: "I would be very annoyed that they knew it was unsafe but did nothing about it.
He added: "Common sense says they should have done something."
The report carried out by Southwark Council was requested by a parliamentary committee in 1999 after a 14-storey block in Scotland "went up like a match", killing a disabled resident.
That fire was blamed on external cladding which led to "unexpectedly rapid fire spread".
The committee warned there could be "a disaster waiting to happen", and concluded: "We do not believe it should take a serious fire in which many people are killed before all reasonable steps are taken towards minimising risks."
Harriet Harman, Labour Party deputy leader and MP for Camberwell and Peckham, said she would raise the revelations with Communities Secretary John Denham.
She said: "This is exactly why a public inquiry into the fire is essential."
A statement from Southwark Council said: "The safety and well being of our residents is a priority for the council and we reject any allegation that we do not take these responsibilities seriously.
"The fire at Lakanal was complex with a number of issues that are being investigated by a number of authorities, including the council."
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