This is an odd one Ian,
earlier today I was able to reproduce the problem when viewing your site.
I then went directly to bing.com and entered the following search:
This gave 3 main results but a listing of other related results.
After doing that search on the bing site, I cannot reproduce the problem on your site, I get the results shown in the attached screen shot.
I asked Ray to test it after I started getting the 30 results, and he is still getting only 3, I asked him to go over to bing.com and use the same search I did:
but He didn't have the same results of returning 30 after doing the search on bing.com
looking through Google, there seams to be a lot of people having similar issues with the bing api returning incorrect results.
Do you get the same results if you put search page on the www.yellowcircle.co.uk domain rather than hosting it on another domain?