Fill gaps above Window

[simonb873]

Hi all, I was cleaning the gutters, and while I was up on the ladder, I thought I'd check the windows. Our windows seems to have a large gaps above the frame. The mortar looks cracked and I believe this is our source of our water ingress and mould forming around the interior window frames and walls.

Should I fill with backer rod and then caulk?

Thanks in advance for any advice.

Cheers

 

[Swwils]

Show wider angle photos and also inside photos of reveals