If any of your circumstances change it's important to tell your insurer. If you don't and then try to claim, even for an unrelated issue, your whole policy may be invalid.
You should tell your insurer about any change, even if it's just your address. This is crucial as it reduces potential problems in the event of a claim. Trying to get insurance after you've had a policy cancelled is very difficult and expensive.
A change in circumstances includes moving jobs, as insurers believe this can affect your risk. You may also save on insurance if you're in a stable relationship – for instance, living with a partner rather than being listed as single.