Knocking in the roof

[Rock Studly]

Just dusted the sag off after a long period of inaction - mainly due to the weather. Took her for a spin at the weekend and she seems to have developed quite a loud knocking in the roof, at the front and slightly to the left of the rear view mirror. Sounds like something has become detached but I am not sure whats in there. Any thoughts?

[D14 AYS]

Check bonnet catches are tight.

[rolex]

Could be a robin, check for a nest