Backed by artwork from her current album and the church's organ pipes, Marling opened the set with a full band, before stripping back for an extended solo acoustic session and then inviting her group to return.
The whistling outro of 'Night Terror' during the solo set drew applause from the crowd, before Marling introduced an as-yet unnamed new song, featuring the lyrics: "Where does my lover lie/ I don't love, I just lie/ Pray, pray for me."
Marling then explained that her album's bonus track 'Flicker and Fail' was co-written by her father Charles, "but he doesn't get any credit for it".
She noted that her two sisters were in the audience and joked that they were well aware of her father's love of Shakespeare's phrase: "How sharper than a serpent's tooth it is/ To have a thankless child."
Marling closed her acoustic set with 'Night After Night', before her backing group returned to the Westminster stage.
As on the rest of her cathedral tour, instead of introducing the band, Marling let each member reveal a fact they had learned about the venue.
The crowd were told that Westminster Central Hall hosted the first ever performance of Joseph and his Amazing Technicolour Dreamcoat, while its basement café was used as an air raid shelter in WWII.
Marling explained that she and her band were part of the "anti-encore movement" and quipped before 'I Speak Because I Can' that if you liked encores, then this was the last song, and if not, that it was the second-last.
Laura Marling's full setlist was as follows:
'I Was Just a Card' 'The Muse' 'Ghosts' 'Don't Ask Me Why' 'Salinas' 'The Beast' -- 'Goodbye England (Covered in Snow)' 'Night Terror' 'New Song (Pray For Me)' 'Flicker and Fail' 'Night After Night' -- 'My Friends' 'Sophia' 'Rambling Man' 'I Speak Because I Can' 'All My Rage'