Jess Brammar, editor of the news channels, phoned around presenters to deliver the news.
Along with Croxall and Brown, they spend the majority of their time fronting the UK channel.
A number of presenters are expected to leave the BBC altogether.
BBC NewsBBC News
Other presenters may be found work on alternative news shows, such as BBC1 bulletins.
They include Matthew Amroliwala, Yalda Hakim, Christian Fraser, Lucy Hockings, and Maryam Moshiri.
The new service will be a version of World News by any other name, a second person said.
There are definitely questions here about what this means for the domestic license fee paying audience.
This was despite many having decades of live presenting experience.
Fraser, for example, frontsThe Context, which broadcasts in the UK.
Amroliwala will also be familiar to British audiences having anchored election and other political coverage.
There has been an exodus of journalism talent from the BBC in the past two years.
Tim Davie, the BBC director-general, said last month that the corporation needs fewer news presenters.
Sorry to be blunt.
It will be anchored from London during UK daytime and evening, and from Washington D.C. and Singapore overnight.
