The prime minister was widely criticised for meeting with emergency service workers at the site but not with survivors who had lost everything in the blaze.
In an article to mark a year since the fire, which killed 72 people, she admitted the immediate response to the disaster, including her own, was “not good enough”.
Writing for the London Evening Standard, she said: “It was a tragedy unparalleled in recent history and, although many people did incredible work during and after the fire, it has long been clear that the initial response was not good enough.
“I include myself in that. The day after the disaster I made the first of a number of trips to the site, thanking the firefighters for their work and holding a short meeting with the team in charge of the response.”
She added: “What I did not do on that first visit, was meet the residents and survivors who had escaped the blaze. But the residents of Grenfell Tower needed to know that those in power recognised and understood their despair.
“And I will always regret that by not meeting them that day, it seemed as though I didn’t care. That was never the case.”
Ms May visited the site of the disaster the day after the blaze and met with firefighters and police officers working at the scene. However, she was kept away from survivors and members of the public as aides feared she would be a target for the anger that swiftly developed in the hours after the fire.
She was heckled as she left the scene, with bystanders shouting “resign” as she stepped into her car and was whisked away.
A year on, Ms May said “real progress” was being made on rehousing Grenfell survivors and ensuring those found to be responsible for the disaster are held to account.
She said no decision had been made about what to do with the site of the tower but that it was her “personal commitment that the bereaved, the survivors and the community will lead the process” of deciding.
Ms May said she was determined to avoid another Hillsborough-type scenario, where survivors and families of the victims are forced to wait years to establish what happened.
She said: “This litany of obfuscation, evasion and delay must not and will not be repeated with Grenfell. That’s why I did not hesitate to set up the public inquiry that began taking evidence last month – and why, after hearing first-hand the concerns of those who lost relatives and friends, I decided to appoint extra members to the inquiry panel to broaden its experience and insight.”
To mark the first anniversary of the fire on Thursday, the charred tower, which has been covered with white material, will be illuminated in green for several nights, as will 12 nearby tower blocks, 10 Downing Street and other buildings across the country.
A series of vigils and memorial services will take place around the tower, while children from nearby primary schools will be invited to plant two camellia bushes in the garden of No 10. Local children will be encouraged to wear green to school on Friday as part of a “Green for Grenfell” day to remember the victims.
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