The decision was taken to lift the caps and see what the state of the wall was underneath.
I knew it wasn't going to be good, but I didn't expect what we found. This is supposed to be solid, waterproof...
The "mortar" was cleared off down to the solid surface.
The caps were then replaced with a large dollop of cement underneath.
The gaps between caps have been sealed with cement.
On the front face, the base of the stack has been re-rendered and the flashing bound into the wall. Luckily the bricks are still strong and there was no need to replace them.
