The publication of the Sue Gray report is commanding a level of anticipation scarcely seen even for a visit by Santa Claus, or a new Adele album.

Boris Johnson and allies have repeatedly stressed the importance of waiting for her report before jumping to any rash conclusions about the ever-expanding list of drinks and soirées in Downing Street.

What we can henceforth call the ‘Sue Gray defence’ - a refusal to comment fully on a perceived wrongdoing pending the decision or judgement from a third-party - is a common and often quite sensible tactic for business, charities and others.

In this case, it has done the Prime Minister no favours, leaving three clear lessons to learn:

1) There’s a big difference between internal and independent
A policy of silence can work well if your client is waiting to appear in court or tribunal, whether as a witness or defendant, or if they are in some way involved in or impacted by that legal process. That’s because, in this country at least, courts are likely to be trusted and well-respected by media and stakeholders - and indeed protected by contempt of court legislation.

There’s a big difference between that, and an internal inquiry or investigation. That’s not to say that internal investigations cannot have rigour and integrity, because with the right governance they can. Nonetheless, it will be harder to persuade stakeholders of its integrity than is the case with an external investigation.

The fact that Johnson is so keen to wait for the report suggests he isn’t too worried about what it will say. Ultimately, Johnson is Gray’s boss, a clear conflict of interest, and it has been unclear what the remit or timescale of her report is, making it a very hard sell.

Communicators must also be wary that if we are seen to block legitimate questions in order to enable the rich and powerful to hide behind flimsy non-regulation, it will backfire on clients, and our profession as a whole.

2) Raising expectations about an inquiry outcome is risky
Raising expectations about an inquiry outcome, suggesting to stakeholders that it will “give you all the answers you need” or mean you can “draw a clear line under the matter” is risky. It may very well not do so - you never know whether you’ll get the result you want, and anyhow different audiences may have different interpretations of its meaning.

Organisations or individuals sometimes claim to have been “vindicated” or “given a clean bill of health” after findings are released or a judgement is made. The truth is often far more nuanced, namely that a very specific factual or legal point has, on the balance of probabilities, been found in their favour. If certain types of accusations get to the point of being investigated or decided in a court of law, then even a ‘not guilty’ verdict may not assuage doubts and salvage reputations.

In the case of Sue Gray’s report, the Prime Minister must be aware that even if it vindicates him, it will be pored over and have holes picked in it by media, the opposition and others.

3) You must consider how long you will remain exposed
An organisation or individual considering the Sue Gray defence needs to consider how exposed they are, and how long they are prepared to remain exposed.

Some, which are less prominent, may be able to put out a ‘we will wait for the investigation’s findings’ statement, to avoid fanning the flames of a media storm that may only last a day or two. Once out of the limelight, they’ll be able to deal with the fallout in a less public way.

In Boris Johnson’s case, his position is so high-profile, and his opponents and media so numerous and well-resourced, that a Sue Gray defence is just going to give them space to attack him. A high-profile organisation facing intense, sustained public scrutiny should be aware that declining to meaningfully respond to clear questions just hands their critics the opportunity to set the narrative.

While the PM’s use of a Sue Gray defence appears ill-judged, there are other occasions on which it may be the best possible option. Remember; no two crises are alike, and communications responses should never be off-the-peg.

Tim Toulmin is the managing director of Alder