Outside Source proving it's a poor vessel for breaking news.
Is it specifically the OS format or that it's a World simulcast that makes it not work?
I flipped over to the BBC News Channel briefly when I heard of the Damian Green resignation, but because the coverage was a simulcast, there was that strange 'World-friendly' presentation which makes it feel like you're watching a non-UK broadcaster cover it. I flipped briefly to Sky then decided to wait until the Ten O'Clock News...
(Personally I'm not a fan of Outside Source. Feels incredibly dated)
To be fair, it broke at about 20:40 and they did spend the time up to the top of the hour on it before OS led on it, but yes the OS format does not deal with domestic news well, breaking or otherwise.
What I really don't like is when a domestic story - which would perhaps be the lead on the NC at 20:00 or 22:00 - airing in World's break at 21:15, usually with a brief package cut short for a sting as World rejoin.