Thanks for the reply Jason.
SOURCE TYPE PARAMETER
I had read about the Source Type parameter, however I was happy to have "Web" as the default. As a test I added both News and Images to the query and got the following results:
Sources=Web+News: Works as before.
Sources=Web+Images: Invalid API Key.
Sources=Web+News+Images: Invalid API Key.
Sources=News: An unknown error has occurred.
Sources=Images: Invalid API Key.
Sadly couldn't see any examples in that link to MSDN of how to add the parameter, however I guessed at "&Market=en-GB" which I placed at the end of the query string, however it did not change the results.
I've implemented those changes and all working great. In fact I changed the highlight from <strong> to a CSS style to change the background colour.
API RESULTS ARE LESS USEFUL
All those extra touches are great, however if I can't get the results that the API is returning to better match the results that I'd get from a bing.com search then sadly I can't see the Bing Search Toolkit being of any use to me on the site I am developing.
I've read many other people posting online that the API returns results that are significantly different from bing.com. What is WebAssist's comment on this situation and what is the solution?