Maybe not in the UK, but here in South Carolina, cat theft is considered a serious crime with serious fines and prison time. 2021-2022 Bill 3991: Nonferrous Metals - Catalytic Converters https://www.wistv.com/2021/05/25/new-sc-law-combats-catalytic-converter-thefts/ https://www.wistv.com/2021/06/06/2-jailed-violating-new-sc-catalytic-converter-law-officers-say/
The police in the major metropolitan areas of the USA will not respond to calls about catalytic converter thefts either, anymore. They tell the callers to talk to their insurance company.
[Offtopic]Parents house burnt to the ground (think 500k$, natural gas and electricity had been cut off long before). Reported it and eventually went before magistrate to question why Police never investigated. By that time, years had passed so other than (literally) my day in court, nothing happened. But I doubt same Police would care if my cat got stolen...[/Offtopic]