Hi Nigel, I am using Woothemes Canvas
Here is a link to an install I use for testing, it is exactly the same as the live site. You will see that some captions are longer
and some much shorter.
On this page the captions are just random mimicking the live install in the length:
https://heremiami.com/wordpress/fountains/
Also it strips out the
line breaks in the captions, here is a duplicate page without the [peg] shortcode where you can see the line breaks:
https://heremiami.com/wordpress/fountains-2/