The report reveals that :
- Poorly cut insulation left gaps of up to 5cm meaning air could rush through the cladding and fan the flames;
- There were gaps of up to 15cm after the new windows went in and none of the uPVC frames were capable of withstanding a fire for more than a few minutes;
- Insulation used on the block was either 'flammable' or 'highly flammable' - as was the 'core' of the new cladding on the outside;
- An 'absence of door closers' meant that many doors failed to close as people fled, allowing the fire and smoke to spread easily;
- Firefighters could only get one fire engine to the base of Grenfell because of new landscaping;
The key conclusion is that the fire would not have spread beyond Flat 16 - where it started - and nobody would have died - if the building's outside had not been re-clad.
This was made even worse because the insulation used in the refurbishment, carried out between 2014 and 2016, was flammable.
Only one in five of all fire door closers were working properly, meaning the smoke and flames spread through the core of the building at speed.
And firefighting facilities were poor, with no 'wet rising main' pipe meaning fire fighting water could not be easily fired to all floors.
New landscaping at the base of Grenfell also made it impossible for more than one fire engine to park at the base of the tower.
It appears the only real benefit of the new refurbishment was that it did stop the tower collapsing, but only after it accelerated the fire that killed 71 and left hundreds homeless.
Grenfell United, the main group for survivors and bereaved families of the fire, said in a statement: 'The report is shocking but it is not surprising to those of us that lived in the tower. It was clear to us the refurbishment was shoddy and second rate. We raised concerns time and time again. We were not just ignored but bullied to keep quiet.'
It continued: 'It's an industry that is broken. It's also an industry that has been allowed to get away with this behaviour.
'Six people died in a fire at Lakanal House in 2009 and the Government failed to act and make changes to regulations that would have stopped a fire like that happening again. Tonight we know people are going to sleep in homes with dangerous cladding on them.
'It is vital the police investigation and the public Inquiry uncover everything that led to the fire and that the Government now actually act so that this can never happen again'.
According to the report, seen by the Evening Standard, the 2014-2016 refurbishment of the west London tower block failed to meet fire safety standards and 'deficiencies' in the new facade helped the fire to spread up the building's exterior.
The report, by fire investigation experts BRE Global, was quoted in the Evening Standard as saying: 'Grenfell Tower, as originally built, appears to have been designed on the premise of providing very high levels of passive fire protection.
'The original facade of Grenfell Tower, comprising exposed concrete and, given its age, likely timber or metal frame windows, would not have provided a medium for fire spread up the external surface.
'In BRE's opinion ... there would have been little opportunity for a fire in a flat of Grenfell Tower to spread to any neighbouring flats.'
Dated January 31, the report was prepared as part of the police investigation into the June 14 fire.
It also identified flaws with the cavity barriers, window frames, 'door closers' and flammable insulation and cladding, the paper said.
Cavity barriers were installed back to front or upside down and were 'insufficient' to bridge the gap between the surface of the building and the cladding, creating a chimney-like effect that aided the spread of flames.
Window frames were narrower than the gap they were placed in, meaning fire could spread around the frame, on to the building's facade and back into other flats.
There was also a lack of 'door closers', meaning that when residents fled, their flat doors stayed open, allowing the fire to spread into the lobby.
The absence of a sprinkler system and the narrow single internal stairwell also breached building regulations.
The Met say they are upset the report has been leaked.
A spokesman said: 'Our aim is to carry out an investigation that has integrity and if it uncovers evidence that any individual or organisation is criminally culpable we want that evidence to be tested through the judicial system.
'As such we are disappointed that an interim draft report appears to have been leaked and published. To protect the integrity of the investigation the MPS will not confirm specifics of the ongoing investigation.'
The force added that 'the heart of our investigation is and will continue to be the families of those who lost their lives; those for whom Grenfell Tower was home and the local community so impacted by events that night'.
How Grenfell Tower was engulfed in just 15 minutes
The report has given the most detailed account yet of how a fire from a fridge spread and killed 71 people.
1.) The fridge in Flat 16 on the fourth floor sets alight on the evening of June 14, 2017, next to a tilt-open window that was dangerous because it offered 'no substantial barrier' to the fire.
2.) Within minutes the flames have risen out of the window and ignited the flammable core of the cladding and/or the flammable insulation all installed in 2016.
3.) The fire quickly spread from floor to floor as gaps in the 'cavity barriers' cause a deadly chimney effect and spreads as droplets of flammable building materials fall.
4.) Fire spreads inside through open windows deficient in the same way as the one in Flat 16 where the blaze began.
5.) Flames and smoke spread into the centre of the building as people try to flee and the faulty or non-existent door closers mean that fire doors fail to contain the blaze.
6.) The whole tower was engulfed within 15 minutes, witnesses and survivors said, but today's report does not give a timeframe
