Chantyranger, you might inquire at Cecil Sharp House in London; they have a website. I'm just rescimming the relevant book above and could find no further reference, but there seemed to be hope for real recorded shanties. The only field recorded traditional sea songs I've been able to purchase are ones done by Lomax in the Bahamas, recently released as a CD by Smithsonian; these were recorded at various house parties with lots of noise and an occasional clarifying question by an incredibly young and naive sounding Lomax.