Thank you for the welcome.
Unfortunately, the insurance company has not done an investigation. They just called it an accidental fire and that was it.
I was at home at the time of the fire and it was quite scary. It took the fire brigade around 15 minutes to get to us and by that time the roof had already collapsed. Fortunately, the too.s are relatively easy to replace. It was our Christmas decorations that had more sentimental value. My better half is not very impressed.
Fortunately we were properly insured. With most insurance companies an outbuilding is only insured for £2500-£5000, we were insured for £100k. Cost a bit more but I am glad we did it.
Two fire extinguishers will be installed before I move all my tools in.
The only recommendation I can give, is to catalogue everything stored in your garage/house. Photos, receipts etc. The insurance company wanted every item listed individually, who bought it, where it was bought, when it was bought, who paid for it and ideally with receipts.
As I move items into the garage, every item will be photographed and a detailed list will be kept.