Hurrah! It is done. And many thanks to those of you who encouraged me to fix it. I’m so glad I decided not to give up.
For the sewists out there, the fix included undoing part of the hem and neck binding (I didn’t need to take the whole thing off!), taking out the button band top stitching and unpicking the band to detach it from the body, cutting the new band and, well you know the rest.
I’m smiling not only because I like the blouse but because I set up the tripod and learned how to use the timer on my camera.