Primetime first as two black actors star in BBC1's Undercover https://t.co/A9ekPP7lYQ— The Guardian (@guardian) March 8, 2016
Apparently, this is the first time two black actors have been cast as leads on a primetime BBC Drama. It is usually one black actor or they co-star (always the bridemaid etc).
The series is written by the award-winning playwright Peter Moffat (not to be mistaken for Dr./Sherlock writer Stevne Moffat). It is about undercover police officers and death in custody. Jewish-Nigeria Princess Sophie Okonedo stars as high-flying lawyer about to become the first black director of public prosecutions. Adrian Lester plays her husband and the father of her three children.
Moffat was quoted as saying this in regards to BBC's lack of diversity - “even the BBC, which is fairly full of liberal thinking folk (don't get me started on this - OP!), hasn’t got round to sorting this stuff out”.
Labor MP Chi Onwurah also added, that 15 years after Greg Dyke declared the BBC "hideously white", there's still a way to go. She said; “I think it’s brilliant but at the same time also slightly ridiculous that the BBC has discovered that there are professional black families,”. She would also like for people of BAME background (that Black, and Minority ethnic) in roles behind the scenes as well.source
And... no, the C4/E4 shows you watched based on tumblr hyping them is not indicative of british TV's diversity as a whole.
*sorry about the previous source link mods - didn't realise what the link what going to!*