Here are those album-only extras I mentioned. They can be played online, but can only be downloaded as part of their respective albums.
Indigo extras
The House of the Rising Sun (part 1): Dave Van Ronk-inspired melodica bongo fury
The House of the Rising Sun (part 1): Otway-indebted pseudo-satnav nonsense
white extras
On Ilkley Moor Baht ‘At: four-part harmony plus translation for the hard of Yorkshire
The moving-on song: two drums, six chords, no synthesisers
Blue extra
La belle dame sans merci: words John Keats, melody copland smith
Fifty-Two Folk Songs 