The leak of Rachel Reeves's budget was not the result of hostile cyber activity, but responsibility rests with the OBR's leadership, an investigation has found.
The fiscal forecast by the Office for Budget Responsibility (OBR), which revealed the contents of the record-breaking tax rise budget, was accessed at 11.35am last Wednesday, about an hour before Ms Reeves stood up to deliver it.
An investigation ordered by the independent fiscal forecaster soon after the budget found there was "nothing to suggest" the premature access was the result of "hostile cyber activity by foreign actors or cyber criminals, or of connivance by anyone working for the OBR".
"Nor was it simply a matter of pressing the publication button on a locally managed website too early," the report says.
It concluded that "configuration errors" led to "a failure to ensure the protections which hide documents from public view immediately before publication were in place".
"The ultimate responsibility for the circumstances in which this vulnerability occurred and was then exposed rests, over the years, with the leadership of the OBR," the investigation said.
OBR chair Richard Hughes has been under pressure to explain the leak, which he immediately apologised for, and ordered the investigation.
It is also led by Professor David Miles and Tom Josephs, with Baroness Sarah Hogg and Dame Susan Rice as non-executive members.
There was pressure on the small team involved to ensure the full economic and fiscal outlook was published when the chancellor sat down after giving her budget, so a pre-publication "facility" was used.
But this commonly used device created a "potential vulnerability if not configured properly" and had not received the same amount of attention by the OBR as it had placed on security of communications with the Treasury "during the long period of run-up to the budget".
The report said
An outside web developer, who has helped the OBR team since it came into existence 15 years ago,
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