Cold awakening

It would happen on the coldest night of the winter so far. By 5am I realised  the boiler was out because the bedroom was freezing. We got fan heaters going, brought Norwestie into the bedroom, went back to bed and cursed.

There's an optic gets covered in soot, and that knocks out the burner. After dawn and after breakfast I went outside. I cleaned it and this is what it looked like then. It worked again.

I know other places were a lot colder last night, but I felt as the sun came up it was the coldest dawn ever. See extra.