It was thought it could be the report that could trigger the resignation of the Prime Minister. It still might.

But what has been published today is unlikely to satisfy those who have demanded maximum accountability and full disclosure after an investigation was launched into reports of parties at Downing Street and Whitehall during lockdown which may have been unlawful. Political editor Paul Francis reports.

Sue Gray, the senior civil servant in charge of the investigation, has been hampered by the unexpected intervention of the Metropolitan Police.

It requested the report limit some of the detail which might compromise its investigation into whether charges should be brought.

In the report, Ms Gray admitted: "As a result of the Metropolitan Police’s investigations, and so as not to prejudice the police investigative process, they have told me that it would only be appropriate to make minimal reference to the gatherings on the dates they are investigating.

"Unfortunately, this necessarily means that I am extremely limited in what I can say about those events and it is not possible at present to provide a meaningful report setting out and analysing the extensive factual information I have been able to gather."

The report said: “Against the backdrop of the pandemic, when the Government was asking citizens to accept far-reaching restrictions on their lives, some of the behaviour surrounding these gatherings is difficult to justify.

“At least some of the gatherings in question represent a serious failure to observe not just the high standards expected of those working at the heart of Government but also of the standards expected of the entire British population at the time.

“At times it seems there was too little thought given to what was happening across the country in considering the appropriateness of some of these gatherings, the risks they presented to public health and how they might appear to the public.

“There were failures of leadership and judgment by different parts of No 10 and the Cabinet Office at different times. Some of the events should not have been allowed to take place. Other events should not have been allowed to develop as they did.”

In response, North Thanet MP Sir Roger Gale tweeted: "Even though filleted this report is a damning indictment of the culture that has prevailed in Johnson's Downing Street.

"This Prime Minister has clearly 'inadvertently' misled the House and he must take the consequences of so doing."

Talking to Sky News this evening, Sir Roger said the country "cannot go on like this".

"We need honest leadership and I am afraid I do not think we are getting that at the moment," he added.

Sir Roger said the government should be concentrating its efforts on tackling the "international crisis" in Russia and Ukraine and, domestically, the cost of living crisis.

"While the can is being kicked down the road, the basic problem remains the same, we are being led by someone who Sue Gray describes in her report, obliquely I grant you, as showing weak leadership. Mr Putin does not understand weak leadership.

"I do not believe Mr Johnson should lead us into the very rough waters that I think we are going into at the moment."

In the Commons this afternoon, the Mr Johnson apologised to MPs but said it was not enough to say sorry. He added that he accepted the findings of Sue Gray's report and announced immediate changes to way Downing St and Cabinet Office would be run.

He said: "I get it and I will fix it. I know what the issue is – it's whether this government can be trusted to deliver, and I say, yes we can be trusted to deliver."

Labour leader Sir Keir Starmer said there could be no doubt the PM himself was now subject to criminal investigation.

He also accused the PM of insulting the public's intelligence and hiding behind a police investigation as he "gleefully treats what should be a mark of shame as a welcome shield".

How did we get here?

When ITV broke a story late in December that featured footage of Boris Johnson’s senior advisers jokingly rehearsing how they would deal with media questions about Downing Street breaches of Covid rules, few would have predicted events that followed.

The actual press briefing never happened. Instead, one of the PM’s chief advisers, ex-journalist Allegra Stratton, quit in disgrace.

It set in train a series of events that has placed a question mark over the Prime Minister’s judgement and political future. Over the following weeks, he was confronted by revelations about alleged Downing Street breaches of the rules on numbers permitted for what were termed ‘social gatherings’.

He continued to insist that at all times, the rules and guidance on these gatherings had been complied with.

The evidence for this was, for some, flimsy and unconvincing and the Prime Minister’s assertion every time he was interviewed that the rules were followed started to sound tired.

As further claims were made and leaks about other parties grew, the PM eventually buckled and announced there would be an inquiry. Ms Gray, a senior civil servant, was asked to look at the nature and purpose of the gatherings, including who went to them "with reference to adherence to the guidance in place at the time".

Among the most contentious of these gatherings was the now infamous one held in the Downing Street garden in May 2020. The PM had insisted he had not been present at this event.

It turned out he was. He had to issue a deeply embarrassing apology to MPs the following week to admit he had attended – although he stuck to his belief that it remained a work event.

The PM was distracted, firefighting internal dissent from MPs over the introduction of new Covid restrictions. In late December, more than 100 backbenchers voted against the introduction of the measures, a significant rebellion.

Meanwhile, restless MPs talked openly about calling for a vote of no confidence in the Prime Minister, believing his authority was draining away.

Labour pulled off a minor coup with the defection of one of the Tory MPs unexpectedly elected in one of the “red wall” seats in 2019.

It briefly galvanised the PM during a rowdy PMQs and heartened some of his loyal supporters. The threat of a vote of no confidence receded.

If the long-awaited report is short on detail and culpability, the PM is likely to face some hostility from some of his own MPs, not just the opposition parties.

And there is every possibility that there could be casualties along the way. The question is whether today’s update points the finger at civil servants or politicians. First reading suggests both may suffer.

One of Gray’s more wounding conclusions finds "serious failure to observe high standards" at No 10 and "failures of leadership".

That uncompromising tone could spell bad news for the PM.