Yes, outside walls.
No changes have been made to any ground levels, so pretty sure nothing it built up higher than the damp course level.
The house did have some recent new glazing before we moved in, and the damp is under a window and either side of a sliding door, so it may be that they are not sealed and water is coming in there.
I'm no expert however, so I'm just guessing and using some logic. Got a few PMs to follow up, so I'll get a few opinions and quotes and take it from there