Haven for rape victims

8.30am On arrival at HQ I meet Detective Inspector Andy Rose, who heads the Sapphire unit. There has been an allegation of rape overnight, so it's all systems go.

The response is a two-pronged approach of care and evidence and over the next couple of days I will get to see this step-by-step process in action.

9.10am I head down to the crime scene, a residential address, with the police and we meet the borough forensics team. Uniformed officers have been posted to secure the premises and log who goes in and out. There will be a police presence here until the crime scene is closed and forensics are satisfied they have collected all potential evidence. "We're not handing the place back until we've done everything we can" says the head of forensics.

10am I have donned a white forensic suit and overshoes, ready to have a look around, but at this stage there is a lot of waiting around while the experts go in to assess the scene and take photographs. They are meticulously thorough in their initial investigation with maximum precautions in place - officers cannot even enter until the forensic team has given the all-clear.

11.30am Inside the crime scene, we are given an account of the findings - where the alleged offence happened and any other places evidence-gathering will focus on. Forensics have already identified the two rooms which they need to concentrate on, mainly from the preliminary police report, but have ensured everywhere has been photographed and protected in case more details emerge at a later stage.

11.45am The process of "forensicating" begins by seizing clothing, bed sheets and any other items recalled by the victim. For rape offences, retrieving tissues, condoms and their wrappers could obviously provide vital evidence and, if there is an allegation of being drugged, any containers that could have been used for drinks are sent to the labs.

12pm I am shown how a Crime-lite works. This special light source brings up stains on surfaces by making them fluoresce differently - safety goggles have to be worn during this stage - and forensics have scoured furniture in search of any evidence. Stickers have been attached to all the stains that need to be examined in the labs.

12.15pm The team start documenting and bagging-up all of the items to be forensically tested in brown police evidence bags. I am told: "Everything is sealed before we leave the premises." Once again, I am convinced of the utmost care and attention that goes into such investigations - everything is recorded in photographs, diagrams and written reports, making sure the case is water-tight if it goes to court.

2pm I arrive at Feltham police station where I am met by a Sexual Offences Investigation Trained (SOIT) officer.

After an allegation is made, a SOIT officer will see a victim within one hour to get the bare bones of the case for the investigation but will then become the point of contact and see the person through the entire process. This helps to build up a rapport and maintain consistency, which is vital to both the police and victim.

At the first stage the SOIT officer may also use an early evidence kit, consisting of mouth swabs and urine samples, and book "the earliest possible appointment" at the Haven, a specialist centre for anyone who has suffered a rape or serious sexual assault, which I will visit later. Early retrieval of evidence from both the crime scene and person is vital to the investigation.

At the police station the SOIT officer is about to do a full video interview with a victim in the Achieving Best Evidence (ABE) suite but I am shown round beforehand. These facilities are used for interviewing victims of sex and violent crimes or vulnerable people with an officer in the control room next door watching on screen and one or two officers conducting the interview.

All children have an appropriate adult with them as a comfort to help them through the process and make sure everything is fair, which protects both them and the police.

4pm My last appointment of the day is at the Haven in Paddington, which is used by Hounslow Sapphire unit as a safe and private place to take victims for collecting evidence, testing for sexually-transmitted diseases and offering practical help and counselling. There are also Havens in Whitechapel and Camberwell if there are no available appointments in Paddington.

Far from the trauma associated with the crime scene and efficiency of a police investigation, the Haven is an oasis of calm.

Ninety per cent of referrals come from police, although anyone can make an appointment without reporting the crime.

For police referrals the plain-clothed SOIT officer accompanies the victim to the Haven in an unmarked car - it is reassuring for victims not to have to sit in a busy A&E department and be identified as being with a police officer. The SOIT officer said: "They treasure that bit of confidentiality."

The 24-hour, appointment-only service aims to provide a response time of one hour - staff are required to live within an hour of the centre.

For a police referral the SOIT officer will go in and see the doctor to give an account of the case, which is then repeated back to the victim. This means victims do not have to go through every detail when they see the doctor and can focus on what to expect from their visit and be made aware of their rights to take a break at any time or refuse part of the examination.

4.15pm Inside the forensic suite the Haven manager said: "For us it's two things we do in here - care and evidence - we provide medical care and collect any evidence of an assault. As well as emergency contraception, infections like Hepatitis B and possible prevention of HIV, sometimes there are minor injuries that need looking at. For any larger injuries the client needs to go to A&E. Everything we do is documented on forms because they might potentially be needed in a court case. Documentation is key."

At this stage if the victim's clothes are required as evidence they are given to the SOIT officer and then the medical examination is carried out, which may only take a few minutes.

Collecting this evidence can be crucial for people who wish to pursue their case but it can also help if they do not want to take the matter further. The evidence and intelligence can be stored or tested anonymously, helping to build a picture that the police may be able to use in investigating other crimes.

All evidence is kept, which also allows people who may not be ready to deal with what has happened now to do so at a later date. The Haven invites clients who have referred themselves to the centre to come back and speak to a police officer to find out what would happen if they did report the crime.

At the end of the examination clients are able to shower and change in a private bathroom with new clothes provided by the centre for those who need them.

There is also a post forensic waiting room, which is a place to relax before staff talk to the clients about what to do next.

4.45pm At a follow-up clinic people are offered counselling and can have tests for a range of sexually-transmitted diseases. The clinic has a separate entrance to the main centre so that when clients come back they are not reminded of their first appointment. 45 per cent come back for a follow-up visit but, as with everything at the Haven, it is up to the individual to choose what services they access.

When children come come to the Haven there is always a paediatrician. The young person's worker sees the 13 to 18-year-olds who access the centre. She said: "I offer them support and advocacy and give them a space to talk about how they are feeling."

The helpline for rape and sexual assault victims is 020 8683 3300.