Ah, thanks for your replies.
To clarify, at the moment I can see on the radar a flight BAW2DP, which is on closer inspect BA792 flying LHR - TLS. Would I be correct in assuming DP refers to Toulouse? Or is it just some random letter assignment done when the flight plan is filed?
I also note there is a DLH94C, known to pax as LH2228. I suppose that means it is a positioning/cargo flight, but I'm bamboozled as to why Lufthansa Twenty-Two Twenty-Eight is less preferable than the rather dissimilar Niner-Four-Charlie
Well, if the system works!