The Metropolitan Police Service (MPS) has today, 28 October announced the new structure and changes to the investigation into the disappearance of Madeleine McCann.

The investigation into what happened to Madeleine continues but with a smaller team of officers. Officers investigating her disappearance have completed the huge task of bringing together and investigating the massive amount of information held by colleagues in Portugal, the United Kingdom investigation and the private investigators working on behalf of the McCann family.

They are now following a small number of focused lines of inquiry that have allowed them to reduce the size of the Home Office funded team.

Detectives investigating the disappearance of Madeleine McCann in May 2007 have been working through material and following investigative inquiries since the Home Office requested a review of the case in May 2011.

Operation Grange is working to support the Portuguese investigation and this work continues.

While there remain lines of inquiry to follow, the vast majority of the work by Operation Grange has been completed.

This work included reviewing all the material relating to the case which were brought together for the first time and amounted to collating over 40,000 documents from United Kingdom and foreign law enforcement agencies, as well as various private investigation companies.

Officers worked meticulously through the information. Some of the material had to be translated into English, facts had to be cross-referred and diligently analysed to ensure an oversight of what the MPS was examining and to search for new lines of inquiry.

Once this work had been completed the review became a full investigation in July 2012.

The investigation team has taken 1,338 statements and collected 1,027 exhibits. Having reviewed all of the documents, 7,154 actions were raised and 560 lines of enquiry identified, and over thirty international request to countries across the world asking for work to be undertaken on behalf of the Met.

Officers have investigated more than 60 persons of interest. A total of 650 sex offenders have also been considered as well as reports of 8,685 potential sightings of Madeleine around the world.

The Grange team received on average two hundred emails a week, and following the media appeal in October 2013 across three countries, received over 7,000 responses.

For an investigation of this size, the extraordinary circumstances of investigating a missing child four years later in another country, the vast wealth of information and theories, it was always going to be an immense task and required a full team of 29 staff working on it.

With the significant amount of work approaching completion, as with all investigations the MPS has reviewed the staff required to progress the remaining work.

A team of four officers will continue to work solely on the Grange investigation, funded by the Home Office. The enquiry has not reached a conclusion, there are still focused lines of investigation to be pursued.

The officers will continue to be overseen by Detective Chief Inspector Nicola Wall, the current senior investigating officer, and sit within an existing major investigation team on the Homicide and Major Crime Command. This will give them access to officers within that team should they be required to support further operational activity.

Assistant Commissioner Mark Rowley, from the MPS said: "The Met investigation has been painstaking and thorough and has for the first time brought together in one place what was disparate information across the world.

"This work has enabled us to better understand events in Praia da Luz the night Madeleine McCann went missing and ensure every possible measure is being taken to find out what happened to her.

"We still have very definite lines to pursue which is why we are keeping a dedicated team of officers working on the case. We have given this assurance to Madeleine's parents, Kate and Gerry McCann.

"The Portuguese police remain the lead investigators and our team will continue to support their inquiry. They have extended every courtesy to Operation Grange and we maintain a close working relationship. I know they remain fully committed to investigating Madeleine's disappearance with support from the Metropolitan Police.

"The Met was asked to take on this exceptional case as one of national interest. We were happy to bring our expertise to bear only on the basis that it would not detract from the policing of London; and the Home Office have additionally funded the investigation above normal grants to the Met. That will continue at the reduced level.

"I have overseen this investigation since 2012 and am very grateful for the enormous assistance of the media and public so far which, through the appeals, have generated new information and lines of Inquiry. "

Our decision and rationale has been discussed with Mr and Mrs McCann.

Mr and Mrs McCann said: "We would like to thank all the staff from Operation Grange for the meticulous and painstaking work that they have carried out over the last four and a half years. The scale and difficulty of their task has never been in doubt.

"We are reassured that the investigation to find Madeleine has been significantly progressed and the MPS has a much clearer picture of the events in Praia da Luz leading up to Madeleine's abduction in 2007.

"Given that the review phase of the investigation is essentially completed, we fully understand the reasons why the team is being reduced.

"We would also like to thank the Home Office for continuing to support the investigation.

"Whilst we do not know what happened to Madeleine, we remain hopeful that she may still be found given the ongoing lines of enquiry. "

The remaining Operation Grange officers will be deployed to other enquiries within Specialist Crime and Operations.