in short yes
if you don't tell them and you have a claim , when they crosscheck your details they could invalidate your insurance then you would be personally liable for any damages
You do have to disclose it. When the insurer quotes for the insurance, they will ask you if you have had any accident or loss within the past four years. This applies to all motor insurance, whether it is on a car or a motorcycle. If you do not disclose it, you may as well not take the insurance out as it will be void if you withhold any material information. I work in insurance and we do catch loads of people doing this as insurers use a central database called the Central Underwriting Exchange where they log things like claims, convictions, fraud etc, and it is shared between all insurers.
It may not necessarily affect your chances of getting insurance, but they may charge you slightly more that they would if you had not had the accident.