I have similar tripe from them,a few years ago,I had a van with lpg,the insurance never mentioned it when I gave them the reg no,so neither did I . Afer a week or so,i thought I had better enquire if they knew about the lpg,they didn't,and then told me the current insurer would refuse to continue the policy,and I had 7 days to find another. Eventually,I did, but had to get the vehicle inspected and certified by lpg engineer before they would issue the policy.
Another one,I carry a water tank in the back of my van for my job,if it was secured to the vehicle frame by bolts to the chassis,as thee proffesional systems are,I would have trouble getting cover ,as that is a modification,even though it would have been proffesionally fitted,and in the event of a crash, would not move.
So now ,I have a removable tank,secured to the bulkhead by strong ratchet straps, still had quotes for renewal of over £500 tptf,28 yrs driving,25 yrs ncb,clean licence,and in my mid 40s,crazy