A wide-ranging government inspection of police forces has raised a warning flag in Hertfordshire, where the service has been urged to boost efforts to cut crime and keep people safe.

While last year’s Ofsted-style report rated the overall performance of Herts Police as ‘good’, there has since been a deterioration in the service provided.

Her Majesty’s Inspectorate of Constabulary (HMIC) has assessed the local force as requiring improvement in respect of its effectiveness at keeping residents safe, and curtailing crime.

The revelation has ‘disappointed’ Herts Police and Crime Commissioner (PCC) David Lloyd, who has admitted his force’s failings are ‘not good enough’.

HMIC said this week that the majority of police forces do a good job in keeping members of the public safe, with two-thirds graded as either ‘good’ or ‘outstanding’ by inspectors, in a report on police effectiveness.

However, the national overview showed that the police service was not as well equipped to stop crime happening in the first place, as it has been in the past. It warned - for the first time - of a national crisis in the shortage of detectives and investigators.

In regards to the force’s effectiveness in Hertfordshire, HMIC’s report said: “Our overall judgement is a deterioration on last year, when we judged the force to be good.”

It added: “The force’s approach to preventing crime and to tackling anti-social behaviour and serious and organised crime is effective; how it investigates crime and reduces re-offending needs to improve.

“However, the force’s response to vulnerable people is inadequate because of serious weaknesses in the way the force assesses risk and how it supports some victims.”

Inspectors acknowledged that Herts Police had “devoted resources specifically to policing its community” and worked well with partner organisations to ensure it had a good understanding of local threats.

But, “the workforce lacks an evidence base to share good practice on the most effective ways to tackle crime and anti-social behaviour.

“The approach to investigating crime and reducing re-offending requires improvement, particularly its initial response ... and offender management.”

HMIC found that supervisors were not reviewing investigations consistently, and that there were “weaknesses in how the force investigates stalking and harassment cases”.

Herts Police was also urged to “increase its focus on violent offenders”.

A disappointed Mr Lloyd said he had asked for a “full report from the new Chief Constable [Charlie Hall] on what he intends to do to fix this”.

He added: “This failure to identify the risk to certain individuals correctly could – unless the force puts this right – damage the public’s confidence in our force and this must not happen.”

The area of most concern to HMIC was the initial contact with officers and the way the call was processed. This has led to some victims not being properly identified as needing immediate help.

The PCC admitted: “The grading of ‘inadequate’ in the strand relating to supporting vulnerable victims is frankly unacceptable and disappointing. The new Chief Constable has assured me steps have already been taken to fix this, and I’ve now added this as an objective for his annual appraisal.”