[DTV]

I understand the financial approach of "until it's broke, don't fix it" - but this is the flagship piece of physical branding across the entire organisation worldwide. Surely it's beyond time it was updated?

Exactly - if you're fine with your most prominent physical logo being 'out-of-date' 15 months after your rebrand, you didn't need the rebrand in the first place. That should have been one of the first changes they made, the fact they haven't is just symbolic of the organisational shambles that this rebrand has been. 

And I don't understand the pearl-clutching defences of the BBC here.
- If it's too costly to change the flagship sign, then don't rebrand in the first place - the cost of that sign will be a minute fraction of the overall cost of the rebrand.
- The Mail will write negative crap about the BBC regardless, that doesn't mean the BBC should exist constantly in state of inaction.
- I'm sure the BBC needed to get equivalent permission and needed custom-made signage built in 1997, didn't stop them changing the logo over as soon as possible then.