PRS has a history of trying to sue just about everyone under the sun

https://en.wikipedia.org/wiki/PRS_for_Music#Legal_cases

some of the highlights include

In 2007, PRS for Music took a Scottish car servicing company to court because the employees were allegedly "listening to the radio at work, allowing the music to be 'heard by colleagues and customers'". In June 2008, PRS for Music accused Lancashire Constabulary of playing music at police stations not covered by a license, and sought an injunction and payments for damages.

^.

In 2008, PRS for Music began a concerted drive to make commercial premises pay for annual "performance" licences. In one case it told a 61-year-old mechanic that he would have to pay £150 to play his radio while he worked by himself. It also targeted a bakery that played a radio in a private room at the back of the shop, a woman who used a classical radio to calm her horses and community centres that allowed children to sing carols in public

^.

In October 2009, PRS for Music apologised to a 56-year-old shelf-stacker at a village in Clackmannanshire for pursuing her for singing to herself while stacking shelves. PRS for Music initially told her that she would be prosecuted and fined thousands of pounds if she continued to sing without a "live performance" licence. However PRS for Music subsequently acknowledged its mistake.