Or at any rate, I think it's solved. Take a look at the picture below - does that look straight to you?
I hope it does. It didn't before, or not to me. I tried to ignore it, and to tell myself that it would look fine to everyone else, I was just too close, but it was no good: it just wasn't right. One leg of the cross - the bottom one in this picture - looked wonky.
I looked at from all angles and from varying distances, and the more I looked, the worse it got. Something had to be done. In a worst case scenario, the cross would have to be done again from scratch, but I wasn't keen on that idea, so wanted to try other options first.
If you recall, I transfer the design onto the front of the fabric by
going over an outline on the back with small running stitches. Looking at the back, I'd gone over the outline fine - I hadn't gone wrong there. This was actually encouraging - I used the same transfer for both crosses, and the first one was straight, so this one must be too. So, the problem must be with how I had the fabric on the frame.
Tugging it further over to one side wasn't going to work as it was too taught, and I didn't want to risk any damage by pulling at it, so I took it off the frame completely and, after a great deal of measuring and comparing, laced it all back up again.
I'm much happier with it now - my photo isn't quite straight, which doesn't help you judge, but it really is much better. It just goes to show, though - you can't be too precise.
So, back to the appliqué. I'm half way through the third leg:
Two of the appliqué pieces still have their tacking stitches in, which I hope gives you some idea of how fiddly this process is! You can't really tell here, but they aren't yet stitched down properly - I just catch them down at the corners first and then check that they're central, so that they're easy to take off and realign if necessary. Once I'm happy that they're right, I can sew them down properly.
This image also shows the order I'm stitching them on - instead of starting at the top and working my way down, I do the top ones, then the bottom ones, then back to the top, then back to the bottom again, until they meet in the middle. This helps with the spacing, and also helps ensure that I don't veer off half way down, but keep the line of satin pieces central.
You might notice that the left-hand guide stitch is well off; I left plenty of slack in these stitches so they don't leave a mark on the velvet, and it shifted when I stitched the appliqué piece over it. It started off straight, honest!