Horizontal cracks in external render

[munchkin198]

My house (built 1950ish) is non-cavity wall and is mostly rendered externally. Render was redone about 4 years ago. This winter, lots of horizontal cracks have started appearing along one wall, about 2 feet apart, at ground and first floor level (this wall is exposed and west facing, and takes the brunt of wind/rain/storms etc). A couple of weeks ago I noticed that water is also coming through the walls internally on the first floor, in line with the cracks. The cracks are all still fairly narrow but run along the width of the wall. I'm not sure if this is a problem with the render, or a structural issue with the wall bowing slightly. Any thoughts very much appreciated.

 

[ree]

OP,
Is the wall actually "bowing" or bulging, even slightly?
A long straight edge across the bulge vertically and horizontally will show the extent of any bowing.
Pics of the bulge will help, & pics of the interior penetrating water signs will also help?

FWIW:
Your porch roof LH abutment requires the removal of the S&C fillet & the installation of lead soakers & cover flashing - the chimney stack needs the same, & perhaps the back wall porch abutment also needs the same. The porch roof moss needs removing.
You have sand & cement plinths at the base of the walls - the plinths & the low render are bridging the DPC in the wall.