No BBC4 airdate info available that I can find. Makes you wonder though.
Available for preorder.
Season 4 has 12 episodes. So if BBC4 shows double episodes as usual every Saturday, that means 6 weekends to show all of Season 4? 16th June start date anyone?
Maybe 9th June, which goes on the assumption that BBC4 will be showing the two episodes of Sebastian Bergman on 26th May and 2nd June.