Well it turns out that partial seams are not that hard (Anne you were right!) I was quite surprised that once I got the order worked out my table runner went together quite quickly!
I ended up with partial seams in an effort to simplify my design and make cutting and piecing more efficient. I combined where possible squares into rectangles. This left me with a bit of a puzzle in terms of assembly. The centre section of my table runner would have 5 pieces to sew together with some meeting only partially and not a straight line across. After staring at it for a while (about the time it takes to drink 1 1/2 cups of tea and dunk 2 rich tea biscuits) I figured just plunge in and start with the lone rectangle.
I sewed it on 2/3rds of the way and this gave me a nice straight edge to add the left piece.
Then I could sew the long piece# 3 to the bottom edge of these two.