Not too surprisingly. You are not an official crime investigation agency. If a movement list and CCTV is released, it will be released to the police. So make sure you bug the police into starting a proper investigation, which should at least include the list and CCTV images.
It might be prudent to warn the airfield that the police has started an investigation and will come and collect CCTV images at a later date. I don't know the custom at your airfield, but typically these images are kept only for a day or three, after which the tapes are overwritten. A preliminary announcement of investigation should be enough to set them apart. If they don't set them apart, but overwrite them, you can later sue them for destroying evidence. Not that that brings your liferaft back of course...