In the absence of any real information, police took the unprecedented step of asking the pop stars to appear in a pounds 12,000 advertisement in a national newspaper.
Matt Tapp, head of press at Cambridgeshire police, said the investigation was so unique that even the most "old fashioned" of detectives had not batted an eyelid at the suggestion.
"When the Bramleys vanished they left no clues at all and we realised that it would be up to us [the press office] to keep the story on the front pages and keep it there if there was to be any chance of finding the family," he said.
"The Spice Girls have a lot of young fans the same age as Jade and Hannah and we thought that maybe if they would talk directly to the girls they might come back.
"Unfortunately they pulled out at the 11th hour and we had to think of something else."
Mr Tapp has been having to think of something else for the last 17 weeks. "Most of the time my job is reactive. There is a fait accompli - a dead body, an escapee in uniform - and we give out information. This was totally different. We had to rely on the public for their help in finding the Bramleys and the only way to do that was to keep the story alive in the papers.
"The problem was after the first day when you have said they are missing, you can't have another story saying they are still missing. We had to keep finding new lines because there were no new clues."
When the family first disappeared Mr Tapp thought it would be a routine case. Returning from a meeting on Monday, 14 September, he was told they had a case of missing persons. "Mispers", as police call them, happen all the time. Every force in the country has dealt with hundreds. A press conference is called, details released and shortly afterwards someone rings in with a sighting. Usually.
Mr Tapp was confident that this would be the case with Jeff and Jenny Bramley. "There were four of them ... I thought it would be a doddle," he said.
"But over the last 18 weeks I've come to the conclusion that it would have been easier to find Lord Lucan. At least he had a distinctive appearance."
As the centre of the investigation moved increasingly towards the press office and away from the incident room, Mr Tapp realised he was going to need a lot of ideas.
The press office released video footage of the girls, found significant dates - Jade's fifth birthday, Hannah's first day at nursery, the first children on the Internet's missing persons website. Anything at all that would make a story.
After the Spice Girls pulled out, Mr Tapp persuaded Crimewatch to feature the runaways. He was aware the Bramleys had not committed a crime and that the programme does not do appeals for missing people, but with a captive audience of 14 million, he reckoned it was worth a try. "Unfortunately it slightly backfired because the next day people were critical of the fact that the Bramleys had been on a programme about crime when they hadn't committed a crime. But we weren't going to turn down the chance of reaching so many viewers."
Once the car had been found in York and two days later the Bramleys had been spotted, Mr Tapp had plenty to keep the papers interested. "Suddenly we had all the media reaction we wanted and the phones were going mad."
The end came with a call from the editor of a local paper saying he had received a letter. There were six more calls from other editors who had all had identical handwritten letters.
From that moment it seemed that the police investigation had been overtaken by events. They continued to follow up reported sightings but the Bramleys were in control. Once social workers had written their own open letter saying they would not stand in the way of the couple reapplying to adopt the children, it was as good as over.