HBO telecast begins at 9:45 pm (et) here.They are showing the Cleverly fights first.So I would think Barker would go in around 4 am your time.
2:45 HBO coverage starts, Clev vs KO Machine first on tape delay then Romero vs Kiko title fight. barker is on after those 2 fights so it all depends on how long the first 2 fights last.
Are BBC Five Live covering this one? Been a while since they had a live fight on, think Khan v Diaz was the last.
As of these afternoon no, they mentioned commentary of Clevs fight vs the Russian KO King though. (ONLY in Wales though, seems the BBC have lost interest)