Ok the issue with the Room_QR1 perdea mesh is sorted. Had to add another flag to this function call:
mesh.OptimizeInPlace(MeshFlags.OptimizeAttributeSort | MeshFlags.OptimizeDoNotSplit | MeshFlags.OptimizeIgnoreVerts, adjac);
The flag OptimizeDoNotSplit cured the problem of it splitting the verticies and thus increasing the mesh's vertice count
Now to continue with the other errors posted 