Here an excerpt from an article in Hot Rod Magazine from around 1999:
"The HW Cadbury Range Rovers were produced in 1990 for Cadbury, a snack food company based in Great Britain, for a 1991 giveaway promotion in the Middle East. The Range Rovers never arrived, The promotion was in the same time frame as the Kuwaiti invasion and Operation Desert Storm - suppositely something happened to destroy the shipment. It is easily assumed all were destroyed but what really happened to the cars is unknown. Only 10 examples of each are known(?) to have surfaced - some in Los Angeles - some in England."
According to Raed Ammari the ship delivering the models sank. He was able to buy 7 pre-production models that were initially with Mattel's marketing department and these were sold over the years on eBay. He believes that there are a total of 25 models in circulation.