A new 21-page technical guidance note, 'Determining what is personal data', explains and illustrates the Information Commissioner's view of what is 'personal data' for the purposes of the Data Protection Act. The guidance provides many examples to illustrate circumstances when data relates to an identifiable, living individual.
There is an accompanying short Press Release on the ICO website.
The introduction to the new guidance says that they will soon also be producing new guidance on the meaning of 'relevant filing system'.
[Information provided by www.emplaw.co.uk, to whom I express my thanks]