Sexual offences and assaults on vulnerable adults are not always being recorded as crimes.

The revelation has been described as “significant cause for concern” by inspectors carrying out a review on Devon and Cornwall Police.

Her Majesty’s Inspectorate of Constabulary (HMIC) has published an inspection report on crime data integrity for 13 police forces in England and Wales, including Devon and Cornwall. As part of it inspectors examined 54 reports, which were recorded separately on the force non-crime system.

They found that of those, 12 should have been recorded as crimes, but that the force had recorded only two out of the 12 correctly – less than 20 per cent.

Also examined were 120 incident records, with inspectors finding that 117 crimes should have been recorded – but only 98 actually were.

Of these, one was wrongly classified and three recorded outside the 72-hour limit.

The report states: “There is a need for improvement in the accuracy and timeliness of crime-recording decisions.

“The force has a centralised crime recording unit through which crime is recorded, either as a consequence of an incident or recorded directly from the public without the need for an incident record.

“It is estimated that 53 per cent of crime is recorded directly from the public without an incident record.”

Inspectors have recommended that the force “immediately” takes steps to make sure reports recorded on other system, such as those used by public protection teams, are recorded as crimes.

“Proportionate and effective” audit arrangements should be put in place, to assure itself that reports held on these systems are properly recorded as crimes, with particular attention being directed to those involving vulnerable adults and children.

The quality of incident and crime reports “varied considerably,” with some containing no more than basic information, although detailed information was available in records of serious crime.

The force incident management computer system does not have incident opening or closing codes for all crime types, making it difficult to identify crime types from the incident record.

It was recommended that within three months the force should expand its suite of incident opening and closing codes to enable a “proportionate, efficient and effective audit of crime-recording.”

Frontline officers and staff were found to have not received structured training in relation to the national standard for crime recording and it was recommended that within six months the force should establish and begin operation of an “adequate system of training” in crime-recording for all police officers and police staff responsible for making decisions in this area, and ensure those who require such training receive it “as soon as is reasonably practicable.”

The force was found to be operating better in out-of-court disposals, with the majority of cautions, penalty notices, cannabis warnings and community resolutions given out correctly.

However, the inspectors were concerned that some cautions were given to offenders in domestic abuse cases, with national police guidance stating it was “rarely appropriate” in such cases.

Deputy Chief Constable for Devon and Cornwall Police, Bill Skelly, said: “As an organisation we need to fully digest the HMIC’s report and review all of their recommendations. Having said that, it is clear that while there are some areas we must address and we are doing so, the report also highlights areas of good performance, such as our direct public criming processes.

“The report identifies that Devon and Cornwall Police has robust leadership and a sound culture in the way crime is recorded in Devon and Cornwall. We do not deliberately over or under crime – which is what we fully expected HMIC to find.

“It is important to make the point that this report looked at our processes, not how we treat victims or actually investigate crime – this was about the way crime is recorded. It is hugely important that people in Devon and Cornwall have confidence in the way we record crime and this report acknowledges that we have ethical and victim-centred processes in place.

“Of the recommendations raised by HMIC, such as some cases not being crimed but were recorded as an incident, we have already changed some of our processes as a result of initial feedback received, and are in the process of dealing with the others.

"While this has not changed the actual investigation process and service to the victim, we recognise this is a more transparent approach and this can assist in building public confidence.

“Of course crime figures are only one measure of performance. Public confidence in our ability to do our job properly and satisfaction levels among victims and witnesses of crime are other, equally relevant measures.

“Modern policing is all about providing the best service possible with the resources available and learning is a critical part of progress. There will always be lessons to be learnt, that’s how we improve and HMIC has a valuable role to play in that process.

“ I am confident that we record crime ethically and the public should gain confidence from that and we will continue to make positive changes to our processes in areas that have been identified for improvement.”