I'm with John Heath, which is actually through Aviva when you get the docs. I'd be interested to see how transportrisk.com compare if you give them a try.
I had a quote from John Heath and when I mentioned it to a broker who specialise in aviation and SUA policies he asked me to forward the policy wording to him as he didn't like the sound of the Aviva policy, here is the response I got back: quote "Yes I thought I’d seen this. Honestly speaking this programme is done on the back of the BMFA facility with Aviva as what appears to be a “special” agreement with Aviva via their Birmingham office. There is doubt as to whether it would pay in event of say a mid air collision with another aircraft, so I can’t really comment further as this is only in relation to small UAS’s.
Anything bigger than about 25Kg would require normal aviation markets which is what I do, so I guess the old adage is, “you pays your money etc……”
Further, I believe there may be some conflict with the UK CAA and the operation thereof but I would suggest you ask the broker for written confirmation that coverage provided would indeed cover Third Party Property damage and Bodily Injury arising out of a collision with another aircraft and that coverage is in accordance with CAP722 and the UAS regulations" I wonder what the truth is? did you check the cover meets CAA requirements?