We have to freedom of expression - due to common law and EU human rights act being adopted as UK law.
However there are limits according to wikipedia
there is a broad sweep of exceptions including threatening or abusive words or behaviour intending or likely to cause harassment, alarm or distress or cause a breach of the peace (which has been used to prohibit racist speech targeted at individuals),sending another any article which is indecent or grossly offensive with an intent to cause distress or anxiety (which has been used to prohibit speech of a racist or anti-religious nature),incitement, incitement to racial hatred, incitement to religious hatred, incitement to terrorism including encouragement of terrorism and dissemination of terrorist publications, glorifying terrorism,[collection or possession of a document or record containing information likely to be of use to a terrorist,treason including advocating for the abolition of the monarchy or compassing or imagining the death of the monarch, sedition,obscenity, indecency including corruption of public morals and outraging public decency,defamation, prior restraint, restrictions on court reporting including names of victims and evidence and prejudicing or interfering with court proceedings,prohibition of post-trial interviews with jurors,time, manner, and place restrictions, harassment, privileged communications, trade secrets, classified material, copyright, patents, military conduct, and limitations on commercial speech such as advertising.
So I'd report to to local police and they may wonder past or have a word - I've seen them do that with local loud persistant one in our shopping center.