https://www.blacksitemedia.co.uk/blog/photographers-rights-amp-the-law-in-the-uk

Photographers Rights: Taking Pictures of People in Public

Are you breaking any law when you’re taking pictures of people in public? Probably not, but the position under UK law is uncertain.

There are currently no general privacy laws under UK law, but the UK courts must take into account the European Convention on Human Rights, which gives everyone the right to respect for their private and family life. As this is an area of law that has been developing rapidly over the last few years, it is hard to be certain what will constitute an infringement.

The key issue is whether the place the image is taken is one where a person would have a reasonable expectation of privacy. For example, it has been suggested that the right of privacy of a child could be infringed by publishing a photo of them with their parents in a public street.

It is therefore advisable to be careful when taking photos intended for publication, even where the subject matter is in a public place. Failure to obtain a model release for the use of an image will certainly make it harder to sell the picture to stock libraries. They may be able to be sold for editorial use, however commercially they would be needing that all important model release form. (See below)