A law was passed in the UK in 1988 that said computer-generated art could be copyrighted by the person who set up the computer to produce it, even if the person played no role in the generation of the work.
However, in 2010 the UK (as part of the EU) signed on to the WIPO Copyright Treaty, which only allows copyright protection for works directly produced by humans.
The Court of Justice of the European Union has made rulings that machine-generated works are not eligible for copyright, nor are any works generated within a strict framework of rules that limit human creativity. For example, somebody tried to copyright a football game, the court said that even though humans were exercising creativity within the game, the strict framework of the rules of football within which the creativity was exercised made the game ineligible for copyright.
But the UK is no longer part of the EU, so European court rulings are presumably void there (although the UK is still a signatory to the WIPO Copyright Treaty). So I find it interesting that the judge in this ruling has largely reiterated the reasoning of the European court in the matter of the constraints the WCT imposes on machine-generated copyright (“This criterion is not satisfied where the content of the work is dictated by technical considerations, rules or other constraints which leave no room for creative freedom”.)
So on its face this ruling seems to nullify the 1988 law and make AI-generated art uncopyrightable in the UK. It will be interesting to see if anyone tries to establish this explicitly.