Crime scene video, or, Call me Sherlock...

Last week we were walking just outside the town of Larne, at the beginning of the famous Antrim Coast Road. Glancing over our shoulders we saw a large house right on the sea, which seemed to have been burned-out.

A little research later told us that it had been burned early in November, and that the police had not established a motive. I think I might have an idea...