Cracked plaster and cracked brickwork behind it

[Arch_ee]

Hello all, new here!

Recently purchased a project house and learning on the job at the minute. It’s a 1930s end of terrace.

In one of the bedrooms there’s a crack in the plaster under the window, plaster pretty much just fell and can see the brickwork behind is cracked. Have done some googling and brick stitching is apparently the best method of dealing with this? More than happy to do this just wanted to get some
Opinions on whether this is actually the best method!

 

[^woody^]

You need to determine what caused it and deal with that, not just repair the cracking, or it will just happen again.

 

[HERTS P&D]

Post pictures of the outside, also showing ground level.

Any drains or down pipes near by?

Andy