I got a reply back from these people:
"Dear Mr Staines
The underwriters have agreed to cover this activity under our grade 4 hazardous activities, therefore an additional premium will need to be paid, the medical excess on any related claims would increase to £650, no cover under the PL section and 50% reduced cover on PA.
Kind Regards
Kind Regards,
Sorcha Geraghty
Customer Service Team.
Annualtravelinsurance.com"
So basically they're saying they'll do it as well. If you're planning on going with them probably best contact them first so it's all agreed etc and in writing. Dogtag worked out cheaper for me though.
Tim