1930s Cracked Wall, should I be concerned

[Marlborough]

Hi everyone, this is my first time posting. So thanks in advance for any help! I am renovating my 1930s semi.

The spare room above the porch has cracks by the window to the floor. I assume that this is due to a double glazed window being put in in the 90s.
The window looks to be of a wood frame with a single skin brick.

These crack have a small amount of air coming through them. I have removed the wall paper and loose plaster as the plaster is blown on the sides.

I recently had the house rendered and the renderer advise that the pebble dash was not blown and to just use Sandtex microseal paint to fill the cracks

What are my options, do I put in a metal bar for support, ignore it and go back to brick and plaster or something more serious?

Thanks again

 

[^woody^]

There may be some movement of the support within the porch roof.

Firstly, the roof should be checked for any water penetration, which will have affected the bay supporting timber.
But the only way to know for sure would be to open up the roof to check the supporting timberwork.

Randomly strapping the wall without identifying the cause risks it being a waste of time if the bay is still moving.