It is a song called 'Deep Blue Sea' by Grizzly Bear, and the version you are looking for is the Daniel Rossen Home Recording. It is on iTunes.
Sigur Rós - Brennisteinn
Ellie Goulding - Lights
Amy Macdonald - Run
The music in the current BBC Great Expectations trailer is an instrumental piece called "Outro" by M83.
Daniel Pemberton
school
I think it is the instrumtal part of "breathe me" by SIA but i cannot be certain
''Paradise'' The Ronettes.
The music used in the trailer for the BBC series "1864" on BBC Four is a piece by composer John Lunn. Known for his atmospheric scores, Lunn's music effectively captures the emotional and historical depth of the series. The trailer features a haunting and powerful composition that enhances the dramatic themes of the show. For specific details on the track, it might be helpful to check the BBC's official site or music credits associated with the series.
Deep Blue Sea - Grizzly Bear
artist: Mumford & Sons track: The Cave album: Sigh No More, 2009 http://www.youtube.com/watch?v=Ay1z1Z0p6Xg
Friendly fires - Jump in the pool