A project manager on the Grenfell Tower refurbishment admitted to disposing of evidence relating to the renovation despite knowing a police investigation and public inquiry were underway.
Claire Williams, who worked for the Kensington and Chelsea Tenant Management Organisation (TMO), said she "binned" notebooks relating to the refurbishment upon leaving her role almost a year after the devastating fire.
Ms Williams told the inquiry on Monday "two or three notebooks" containing records dating back to 2013 were lost.
"I left the TMO in May 2018 and I binned all of them but the last one, and [the TMO's solicitors] have possession of the last one which covered probably 2017 and 2018," she said.
Chair of the inquiry Sir Martin Moore-Bick asked: "You binned them even though you knew, by that time, there was already on foot a public inquiry?"
Ms Williams replied: "Everything that was in there I would have thought is actually documented elsewhere.
"I think I just tidied up the desk. I would have looked at them and thought 'There's nothing here that isn't in formal evidence', and so I got rid of them."
Inquiry lawyer Richard Millett QC asked Ms Williams: "Have you ever informed the Metropolitan Police you had destroyed documents which were relevant to their investigation?"
Ms Williams said: "No, I didn't. Because it's not occurred to me. Today's the first time I've ever really had a conversation about this."
She told the inquiry: "There was nothing underhand about it. I was clearing my desk, I looked and decided that everything that was in there was formally represented in minutes or other paperwork and it was of little value.
Ms Williams was questioned after Peter Maddison, her former colleague, disclosed notebooks containing "material of the utmost relevance" to the inquiry last week.
Earlier on Monday morning, the inquiry heard that Mr Maddison and his legal representation will need to give "clear and convincing" explanations as to why he failed to disclose the evidence until now.
The Grenfell Tower Inquiry is in its second phase, which is investigating how the refurbishment of the block was carried out, taking evidence from TMO, Kensington and Chelsea Council and private companies involved in the project.