Which of the following is not a type of compulsory insurance in the UK?

In the UK, compulsory insurance refers to types of insurance that the law requires individuals or businesses to have in certain situations.

Motor insurance is mandatory for all drivers, covering third-party liability in case of accidents. Employers' liability insurance is also compulsory for businesses that employ staff, protecting employees from work-related injuries and illnesses. Public liability insurance for riding establishments can be required under specific regulations that relate to the operation of such establishments.

In contrast, travel insurance is not a legal requirement for individuals traveling, making it voluntary. While it's highly advisable due to the financial risks associated with travel disruptions or emergencies, such as medical expenses abroad, there is no legal mandate that requires travelers to purchase it before a trip. Hence, it is clear why travel insurance is the correct answer as it does not fall under the category of compulsory insurance in the UK.