If you leave it alone for a few years, and your house falls down, it was Death Watch Beetle.

Squirrels are found in parts of Manchester (there are also parts where they wouldn't be seen dead).

My house is roughly the same vintage as Sibelius's; I have been troubled with mice in the ceiling and floor spaces once or twice, but only in hot months. One the other hand, no rodent in my house ever had ambitions to become a drummer.