Google Search
The google search facility will search only the SBS website for images and (if you select the Web tab) for text content. The Google system seems to return a lot of unrelated images from the galleries that fit the search criteria but not the specific image that meets the criteria. Most infuriating. This requires a bit more manual searching within the gallery, perhaps using CMD+F to search for the text within the gallery.
Relevanssi Search
This is a new search plugin that may give more targeted results. Unlike the Google Search the Relevanssi Plugin will search our image galleries but not show thumbnails of the matched results. However it will highlight the snippet of the specific caption or title which, if you go to the gallery, you can find the image using CMD+F to search for the text within the gallery.
Other Catalogues to Search
You can also search the Marlipins Photographic collection using this text catalogue.
You may also find it useful to search the other significant photographic collection the Winton Collection. An index is here.
Also there is the catalogue to the Shoreham Herald Bygones articles.