Thank you all for checking this out. When the post failed to appear I saved the text in my scratchpad and have now re-posted it successfully.

I could remember that others had experienced something similar and kcott's mention of tye's suggestion rings bells. The site did seem to be a bit sticky when I created the post and there was a delay after hitting the "create" button so a time-out of some sort seems likely.

Thanks again for your assistance.