I'm 100% certain that the backend is Google somehow. Do a search on the
BBC homepage and compare the results to those from
Google UK. I tried it with a few select phrases and I got identical results (even the same text 'quoted' at each section). If only Google or the BBC would come forward and say 'yep, it _is_ Google' it would have been a lot more open...Saying that, there's no advertising on the site (the BBC isn't allowed to accept commercial advertisments) so I'm guessing that Mr+Mrs.licence payer have indirectly paid a nice hefty sum to Google and the BBC doesn't want people to know...
That's my 0.02p anyway :)