Thanks for that, 'Radiorail'; until it was pointed out in this thread, I never realised that there are radio stations that only exist on DAB.
I'm bound to say that I find it incredible that traffic alerts remain unobtainable on DAB although, if I'm correct, it seems to me that, so long as there are BBC FM stations in the 'Favourites' list in my infotainment unit, I receive traffic updates regardless of whether or not I'm tuned into one of them or listening to my music on my connected phone from Spotify, Amazon or Apple........I think! I'll have to pay closer attention to see if that really is the case.