Horizontal cracks above windows

Kinellar

I have some large horizontal cracks that run across the whole front of the house above the windows upstairs only. On the outside the windows sit flush upto the gutters so the cracks sit directly behind the gutters on the inside. Do you think the gutters are the issue here or something more major. I can see a very small stair crack in the brick outside near one window also. Any advice would be much appreciated? 
Many thanks

stuart45

The cracks look like they follow the wall plate and then drop down to the top of the lintel.This might indicate some roof movement.
You could remove some plaster for a better idea.