The Plod have no power to seize stereos off their own bat but they haven't done in this case, the local noise abatement team (with an excessively cool acronym) from the Council has. Plod was just there to stand around in order to prevent a breach of the peace in case the students starting get riotous. The Council are normally very patient with noisy neighbours and give warnings before they resort to taking it away. It says they got a warrant so proper process followed. Not a lot of sympathy for the students to be honest they were undoubtably warned a few times and just ignored it so on their own heads be it.
EDIT:
Actually reading the article it doesn't say students just residents so own prejudices showing there but still the same principle though