Mr. and Mrs. Smith and Mr. Drake/ The Sea Nymphs: the group consists of three Cardiacs members (two of them being former Cardiacs members)- Tim Smith, Sarah Smith, William D. Drake. They started out in the 80s and recorded a rather beautiful eponymous (Mr. and Mrs. Smith and Mr. Drake) album on an 8 track. Later around '93 after Mrs. Smith and Mr. Drake left Cardiacs, the three reformed under the Sea Nymphs, and recorded a bunch of tracks with better audio quality than the one made in the 80s, which some of them were eventually shoved into an album. While both albums focus on quieter more pastoral avant sounding folky passages that are definitely easier to listen to if you can't stand the punk noise of Cardiacs (i.e. me dad, who can't really stand Cardiacs but loves the Sea Nymphs), the albums recorded in the 80s does sound quite different than the 90s album. Both should probably be in RIO/Avant-prog.

Spratley's Japs- Project recorded by Cardiacs frontman Tim Smith with singer Joanna Spratley,  Heidi Murphy,Mark Donovan, and Viv Sherriff. The band's sound isn't far off than Cardiacs' sound, but it is rather more psychedelic and less punky. They recorded just one album, it too rather great by the name of "Pony". I say RIO/ Avant-prog, but psychedelic/ space rock also makes sense.