Just noticed on the Surrey Police chief DTL interview on Breakfast, the live camera is 50i, but the keyed in background loop video is 25p. <facepalm>
Since you brought up frame rate does the BBC run all their cameras in 50i? Don’t current cameras allow you to choose frame rate so say photogs in North America (and South Korea) and the bureaus shoot in 50i instead of the typical 59.94 in those regions?
Curious as if the conversion to 50i and back to 59.94 for North America would degrade the picture quality? And if they don’t shoot 50i but the 59.94 what does the conversion the vision mixer or another device.
All studio cameras for news and live pres etc in the UK usually run at 50i . I don't know what the conventions are at UK broadcasters' bureaux in '60 Hz' territories ?
 Except of course for UHD, where it'll be 50p
The BBC News teams and bureaux based overseas almost always follow local frame rate standards. To do otherwise would make pooling, sharing and accessing local content much more complex. So the US BBC operations run at 59.94i (or i29.97 if you prefer that way of saying things) and standards convert. This also avoids the lighting flicker issues you still encounter when running at a different frame rate to local mains. This is particularly an issue on new CMOS cameras without global shutters.
In cases where a crew from London travels to a 60Hz country to shoot content and comes back to the UK to edit, they may chose to stick at 50Hz, but will have to cope with lighting flicker.
Mainstream productions in 60Hz territories will take a common sense decision based on what they are doing.
If you are running local presentation of a sporting event shot at 60Hz, with discharge lit backdrops running at 60Hz, and taking lots of ISOes at 60Hz, then running your operation 60Hz and converting the result makes sense. Also most US trucks are only ever run at 60Hz, and whilst technically the kit may cope at 50Hz, there is every chance that something may not be compatible, or crews may not be used to 50Hz-working. (It's usually stuff like domestic HDTVs in the US that won't accept a 50Hz input *)
If you are creating your own show entirely, shooting your own content, and using your own fly-pack facilities, or a European truck shipped over (yes - that happens!), then running 50Hz can make a lot of sense, as it allows you to bring over content shot 25/50Hz for insert play-in without double conversion (25/50->60->50) or having to remember to shoot & edit inserts in 24/30/60Hz, and avoids conversion at all. However you do have to have a plan to cope with lighting flicker.
(*) ISTR that a US broadcaster with British Open Golf rights (TBS?) chose to remotely produce their coverage in the US, backhauling multiple 50Hz feeds, running their studio at 50Hz, and just converting the end result (not every feed). The biggest issue they hit was in-vision displays not accepting 50Hz inputs... Whilst all European HDTVs sold in shops happily accept 59.94/60Hz feeds, many North American models still don't accept 50Hz.