Rarely, if ever, in British political history has the fate of a prime minister rested on the assessment of  a civil servant working for the government that he leads. By placing his future in the hands of Sue Gray, a senior Whitehall official, Boris Johnson has left himself in a constitutionally compromised position.

Her report is to him, and yet he is also the principal protagonist in her inquiry. Either he is directly culpable for breaching the regulations, wittingly or not, or he presided over the development of a culture inside Number 10 within which they were routinely flouted.

No one is expecting Ms Gray to point the finger of blame at the Prime Minister, and nor should she. Her task is to say what happened as clearly as possible and leave others, notably Tory MPs, to decide on levels of guilt and what constitutes a proportionate response.

But since it involves a government official reporting directly to him, it is for the Prime Minister to decide how much of the report to publish. It is being suggested, or at least not denied, that Mr Johnson may choose to keep back some of its findings.

Dominic Raab, the Deputy Prime Minister, declined yesterday to say whether the report would be released in its entirety, though he also promised “full transparency”.

The best way to achieve that is to publish the complete report. Anything less would encourage a view that there is something to hide and do little to enhance Mr Johnson’s standing either in the party or the country. He is adamant that he has done nothing wrong and therefore has nothing to fear from publishing the full report. He knows well enough that any missing bits will almost certainly be leaked in any case.

Mr Johnson has said he will make a statement to the Commons once the report has been received. If it is only partially published he would be required to justify any editing while prevailing upon ministers and MPs to do the same. Many are weary of having to spend their time hosing down the flames around No 10.

Conceivably, Ms Gray’s report will be so damning that Mr Johnson will be forced from office. But if not, the party needs to use the reprieve for the Prime Minister as an opportunity to put this episode behind it ahead of the local elections in May. A civil war will only benefit its opponents.