Thanks for the reply. The upgrade was of lots of facets of the site. I have a detailed procedure I go through to transfer from the WAMP to live, which includes changing all the links. It worked fine last upgrade when I used the same procedure (including for these gifs). As far as I can see, the links in all the code are correct.
Using Google's inspect element under Resources, Frames, Images I see the Public Houses page has both the correct gif (/wp/wp-content/plugins/new-simple-gallery/right.gif) and the incorrect one (/public-houses/wp-content/plugins/new-simple-gallery/right.gif).
Under scripts it has only one script (/wp/wp-content/plugins/new-simple-gallery/new-simple-gallery.js). If I click on this it shows line 21 to be the default
images: [ 'wp-content/plugins/new-simple-gallery/left.gif', 'wp-content/plugins/new-simple-gallery/play.gif', 'wp-content/plugins/new-simple-gallery/right.gif', 'wp-content/plugins/new-simple-gallery/pause.gif'], //nav panel images (in that order)
When I go into my cPanel and look at the script I put there it has my version on line 21
images: [ '/wp/wp-content/plugins/new-simple-gallery/left.gif', '/wp/wp-content/plugins/new-simple-gallery/play.gif', '/wp/wp-content/plugins/new-simple-gallery/right.gif', '/wp/wp-content/plugins/new-simple-gallery/pause.gif'], //nav panel images (in that order)
(Using Winmerge I have confirmed that the two scripts differ only in this line 21.)
That seems to imply to me that it is picking up my script (and hence loading the correct images) but then for some reason overriding it with the default version. I do not know why or how that could happen. The only thing I can think of is if there is some sort of error in my script (not seen on the WAMP), and this prompts WordPress to pick up the script from elsewhere on my host's system.
Again thanks for any help you can provide.