Under the Road Traffic Act 1998, it is an offence to withhold relevant information when applying for car insurance, so you’re legally obliged to declare penalty points to your insurer. Points are considered ‘spent’ after five years has passed, so an insurer is legally not allowed to increase your premium after this.
Essentially, if an insurance company asks and your points are still on your licence (but your conviction is spent) it is commonly accepted that you should declare it. However, as the financial ombudsman states, if an insurance company cancels your policy after finding out, they will uphold a complaint against the company.
Most expired conviction code endorsements will automatically be removed from your driving record when they’re no longer valid. The length of time they stay on your record depends on how serious the offence was. For example, if you were convicted of drink driving, you have a 'DR10' endorsement on your driving licence, your endorsement will stay on your licence for 11 years from the date of the conviction. The reason for that is that a second drink drive offence within ten years of the first conviction will result in a minimum of 3 years disqualification.
Source:
https://www.keithmichaels.co.uk/convicted-driver-car-insurance/info/how-long-do-endorsements-points-stay-on-your-licence/#:~:text=Under the Road Traffic Act,increase your premium after this