THE Met. Police is planning an overhaul of its Sapphire Units which investigate rapes and sexual assaults, and it is basing many of its changes on the capital’s most successful unit - in Bexley.

In the wake of the police failures in the case of the black cabbie sex attacker John Worboys, forces across the country will now face regular assessments of how they are investigating rape and sexual assault allegations.

Success is patchy and statistic show some forces are five times more likely to secure convictions than others.

In 2002 the Met created its Sapphire Units to deal with sexual crimes.

The units are not a compulsory requirement for borough commanders who decide if they want to fund a Sapphire Unit in their borough and how much resources to devote to it.

Currently only 28 of the 32 London boroughs have one.

But in the light of recent events, the Met has decided to bring all its Sapphire Units under a central command from September.

Every borough will have one, and they will work to a uniform standard.

Bexley’s unit is recognised as the best in the Met and will be used by the new central command as an example of best practice.

In Bexley in 2007/8 there were 15 offences in Bexley and all alleged offenders were arrested and charged.

Last year, the unit was disappointed that it only charged 13 of the 14 suspected attackers.

Detective Sergeant Warren Arter runs the Bexley unit.

With him, he has four Sexual Offences Investigation Trained (SOIT) officers, four PCs and two detective constables.

Above him, is a detective inspector and the top man Detective Chief Inspector Peter Thomas.

Det Sgt Arter said the success of Bexley’s unit is down to several factors.

The first is that borough commander, Chief Superintendent Tony Dawson, gives the unit a high priority, allocating experienced officers to the team, who stay with the unit instead of being rotated every six months.

Secondly all the units SOIT officers are experienced PCs who have seen all kinds of sexual attacks and have made the unit a career choice.

The most experienced lead officer has worked on sexual offences for 14 years.

Det Sgt Arter said Mr Thomas, who is in overall charge of the unit, has worked on murder investigation teams and runs Bexley’s rape investigations in a similar way.

That means the first 24 hours after the attack are treated as crucial and each officer is allocated a specific role within each investigation.

In January, the unit was given its own victims' suite at Bexleyheath police station, where victims who come into the police station can be taken to make their statements in comfort and privacy.

The SOIT officers are on call 24 hours and once a victim calls 999, the SOIT officer must be there within an hour and stays with the victim all the way through the process and afterwards, providing practical help and support.

When a rape victim dials 999, the uniformed officers who receive the call, take with them an early evidence kit, which they will use to take a urine sample and mouth swab from the victim.

The SOIT officer will arrive soon afterwards and will take the victim to The Haven, a specialist rape suite in Camberwell, staffed by forensic doctors.

There, the victim will be medically examined, samples taken and will be offered medication to prevent sexually transmitted diseases and offered counselling.

Afterwards, the SOIT officer will take the victim home and take a brief statement with enough information to begin the investigation.

Arrangements are then made to take a full statement, which can be done on video.

Unusually Bexley’s unit deals with all categories of sex offences from indecent exposure to rape.

This is to make the team aware of who in the borough is committing crimes of a sexual nature, as offenders sometimes escalate their activities to more serious crimes.

In an average month Bexley receives three rape allegations and two of sexual assault.

Only one or two a year involve strangers.

Det Sgt Arter said: “Rape is the most serious offence to be dealt with at borough level and we need the best officers on the case, which is what we have in Bexley.”

Peter Thompson is one of two detective constables on the team and he used to be a SOIT officer.

He has worked on the unit for two-and-a-half years.

He said: "Our work does have an impact on victims' lives and on the community a s a whole.

"It can be quite harrowing, but it is challenging and satisfying work."

One victim of attempted rape in her own home, whose attacker was jailed for nine years, told News Shopper: “The Sapphire Unit was brilliant.”

The woman, who cannot be identified for legal reasons, said: “The officers treated me with a lot of respect.

“They helped me a lot especially when there were times when I did not want to go through with things.

“They reassured me I had such a strong case and my attacker would go to prison.”

Det Con Peter Thompson handled her case, showing her around the courtroom before the trial began and making sure she was allowed to give her evidence from behind a screen.

She said: “I received calls and personal visits from Peter and got a lot of support during the trial.

“Because I was really scared to go out after the attack, Peter spoke to Bexley Council and got me a move.”

She added: “I am pleased now that I did press on with the case.”