[DTV]

I don't get why you think BBC News is a "masterbrand".  BBC is the masterbrand.   BBC News is a sub-brand of the BBC.  And I don't think it should be required to carry the weight of news broadcasting on Radio 2, Radio 3, Radio 4, Radio 5 Live, Radio 6 Music, BBC Local & Regional Radio, BBC World Service and all the other external services, BBC One, BBC Three, BBC News Channel, BBC World News and all the other external TV services.  That's diluting the brand and doing it in such a way as to make the brand seem stretched pretty thin. 

This is why you use sub brands, such as BBC World Service News, BBC Radio News, BBC News 24 and so on, to help carry the load, especially where it makes sense because of the vagaries of the product.  BBC World Service News is very different to BBC News on local radio, so separating that into its own sub brand makes sense.  Same for the news channels.  24 hour rolling news is a very different beast to the roundups on BBC1, so why should the same brand be required to carry those very differing loads?   No, use separate channel brands, like BBC News 24, BBC World News, rather than lazily require BBC News to be all things to all audiences at all times, that just doesn't work.

The BBC and BBC News are both masterbrands, clearly; (for the third time now) that's not what brand dilution is; using BBC News as a uniform brand very clearly does work as it has been the approach of BBC News for over a decade - a decade during which engagement with BBC News services increased significantly around the world and it has established itself as one of the key global news brands.

To be quite frank, these are principles that have been core to corporate branding for several decades now. Your idea of branding seems to be based around a similar logic to those who believe that ITV should bring back the regional identities - it seems not to comprehend that more diffused brands are not conducive to building strong multi-media multi-national brands. That's not to say they can't work as individual brands for limited purposes, but that they needlessly parochialise output in an era where you really need as unified a brand as possible (which has benefits aside from just brand recognition, particularly regarding online misinformation).