FWIW:I should like this to be this will be my last post on the subject, however, if i can help you a little further Stephen i will:
1. If you are privy to further information perhaps it would be generous and helpful to share it. No mind readers on here.
2. Efflorescence in this kind of remedial situation is quite irrelevant - you are chasing a red herring.
Do you believe that all the money, materials and craft that goes into a "damp" situation is to chase out any efflorescence?
Precisely, how will efflorescence affect the application of a tight scratch coat to the extn walls? How will it affect the rendering of the internal walls? I'm asking you for precise details, please.
3. How in the name of God, can the wall be drying-out given the OP's original complaint, and everything that we can see, tells us that the wall is anything but drying out? Have you read a book on this subject and post without prior experience?
4. Why do you refer to the ground level as "the floor"? Now you seem to be suggesting that rendering below the path is of little significance?
5. The brick course below the lower DPC can be seen to be clearly soaked, even with the bad pic.