Keep accident book records for at least 3 years
The Social Security (Claims and Payments) Regulations 1979 require schools with 10 or more employees to keep an accident book, and to retain records in this book for at least 3 years.
Learn more about accident recording and reporting in another of our articles.
You should also keep first aid records
This is not the same as the statutory accident book, although you're free to combine the 2 records if that's easier.
DfE guidance on first aid says you should record:
This list is repeated in Health and Safety Executive (HSE) guidance