The Data Priotection Commissioner is just interested in that the information you are gathering complies with the Data Protection Act
1998. The Police are more interested in being able to use the information for prosecution of miscreants.
In a private property that does not involve looking at the general public, you do not need signs or to register with the Data Protection commision. However, you cannot sight a camera to overlook an area where the general public are. Although, no one will prosecute you for looking at your car on the road (say) but they would if you trained it into the bedroom of the nubile 19 year old girl over the road.
Odd that there is this thread here though! It is what I do for a living you see, check out 'Security inStore CCTV web site'
formatting link
) and see if there is anything there that warms the cockles of your hearts.