Its not unlawful for a private individual to point it into a public area, although the advice of the ICO is that you should avoid doing so as much as feasible. Something taking place in the public domain for all to see cannot also be private at the same time, so there are no privacy issues in doing so. However, there are data management issues to consider with images after they've been captured.
Certainly things
might get sticky if it captures neighbours private property, particularly stuff like barthroom windows and the like.
I know you're a sensible chap anyway, so I doubt anything here will be of much suprise to you.
https://ico.org.uk/your-data-matters/domestic-cctv-systems-guidance-for-people-using-cctv/
Be aware that if you do capture images of scumbags committing crime that as well as DPA (which is the interpretation of GDPR into British law) there is PACE Code D to consider. Don't go slapping images over social media, because not only is it very difficult for the police to use any names or information that arise as a consequence, it may actually jeaporadise any potential prosecution - once a well meaning victim has slapped the images over Facebook themselves the cat is put of the bag, the images are out there, and its then difficult - if not impossible - for a Code D compliant identification to be made if the police release images because the data is already out there in an uncontrolled, unregulated manner.
Also, Brians friends mate Janet saying the villain is Fred Bloggs is no use - in order to have reasonable suspicion with any prospect of a positive outcome they need that person to give a statement and, if necessary, stand up in court and and give evidence to that effect. Simply throwing a name at the Dibble may be interesting to them, and possibly useful for intelligence purposes, but in terms of progressing an investigation it is useless without a sworn statement.
Also, Janet saying the offender is Fred Bloggs becaude of the jacket, or hat, or way they walk is of no use. It must be a facial identification (exception being really serious stuff lime rapes, murders, etc, where there may be corroborsting evidence such as DNA and the like). An identification based upon clothing etc alone is of no use to the dibble.
When the Rozzers do so themselves it has to justified and proportionate with regards to operational necessity for the purposes of the detection of crime, and compliant with Code D in every way, and the rationale for the decision recorded.
