If the condition you're claiming for isn't covered by your policy, or if the policy wasn't in place when what you're claiming for happened, a claim would be declined.
When you apply for cover, make sure your answers are true, full and accurate, or this could result in the policy being amended or cancelled, may reduce the amount payable in the event of a claim, or may result in a claim not being paid.
Your cover is provided by and administered by Aviva Life & Pensions UK Limited and they publish their claims figures every year.