Thank you Muraria. It's our central blocks that differ.
Gitto, if what you say about rows six and seven is true, I must have made a mistake, but I can't see how my grid would assemble so perfectly if I have. Maybe I am missing something simple.
I think by now it's okay to say that in row six I have 14ac, which starts at column three and crosses the box, ending at the edge. If that is correct there can only be a bar between columns two and three, mirrored on the right.
In row seven, 16 starts in column one and ends in column seven, so a bar between seven and eight, mirrored on the left. Are these wrong? Would you mind emailing me, as you kindly did with cockie? I'm on ukrdge at me dot c om