I think that this guide to photographers rights might apply in this case: www.digitalcameraworld.com/2012/04/14/photographers-rights-the-ultimate-guide/
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.
Photographing children
The same laws apply to adult and child subjects, but a child does not have the legal capacity to consent and a parent or guardian must therefore do so on their behalf. Be aware that schools, leisure centres and places where children and adults gather usually have their own photography restrictions.
Although decent photos of children (see our tips for better pictures of babies, children and teenagers) taken in a public place may be fine for non-commercial use, seek permission from the child?s parents or guardians and don?t shoot covertly with a long lens. For commercial images, you?ll need to get a model release signed by the parents.