We survey the crystal and magnetic structures and bulk magnetisation for representative examples of the series of ferrimagnetic tris-oxalato-ferrate(II,III) salts with general formula AFe(II)Fe(III) (C2O4)(3) (A = quaternary ammonium, phosphonium), The compounds all crystallise in two-dimensional hexagonal honeycomb lattices but while some show positive magnetisation at low temperature (Neel type Q) others show a large negative magnetisation below a compensation temperature T-comp (Neel type N). In compounds that exhibit negative magnetisation a discontinuity in the magnetisation is observed at T-t (T-comp < T-t < T-c) indicative of a magneto-strictive transition. In compounds that exhibit positive magnetisation, hysteresis and frequency dependent AC susceptibility indicate a glassy magnetic order at low temperatures, possibly arising from the frustration of random anisotropy domains below a blocking temperature, or imbalance and disorder of Fe(II) and Fe(III).