Various colleagues had some useful suggestions:-

P - I learned something new from my outworkers the other day... Place right sides together as normal. Then turn back the required seam allowance of the width on top — this allows you to see the pattern match where the fabrics meet. Then stitch close to the fold line you have just turned back. When you fold over to the right side you have a normal looking seam but cannot pull it apart to see in between the stitches.

B - Now I wish I'd read this before I hand basted and sewed four double width curtains in an embroidered silky fabric that slipped and slid and drove me nuts. I ended up hand slip stitching each seam before machine sewing in order to pattern match properly, and even then it's not absolutely perfect as the embroidery's pulled the fabric a little off grain in places. This would have quite possibly solved my problem - I'm off to try it with an offcut!

Ph - When joining the fabrics using this method, you must lay it a few mm's off line from the back to allow for the fold over - Stitch very close to the edge.

C - I have also tried this method. It certainly makes pattern matching easier but I also felt it made the seam quite rigid and more obvious.

L — it doesn’t suit all fabrics, but make sure your tension is not too tight and perhaps make the stitch length slightly longer. Using a walking foot also helps if you have one.