The far left/lower area of the inner wheel arch was very rotten, so this too was cut out. Unfortunately this is not available as a stand-alone repair panel, so I had to cut up my lovely new inner wing repair section (sob!) just to get this part. Once again the Portamig did a fine job.
Once the new outer arch lip repair panel was trimmed to fit (with a swage joggled into it for an overlap at the point of welding) I carefully tacked it in place, then seam welded it all the way round. Afterwards a thin skim of filler was added, and rubbed down. I don't have it quite right yet as there are still many high & low areas.