The true nature of the progenitor to GRBs remains elusive; one characteristic
that would constrain our understanding of the GRB mechanism considerably is
gamma-ray polarimetry measurements of the initial burst flux. We present a
method that interprets the prompt GRB flux as it Compton scatters off the
Earth's atmosphere, based on detailed modelling of both the Earth's atmosphere
and the orbiting detectors. The BATSE mission aboard the \textit{CGRO}
monitored the whole sky in the 20 keV - 1 MeV energy band continuously from
April 1991 until June 2000. We present the BATSE Albedo Polarimetry System
(BAPS), and show that GRB 930131 and GRB 960924 provide evidence of
polarisation in their prompt flux that is consistent with degrees of
polarisation of $\Pi>35$% and $\Pi>50$% respectively. While the evidence of
polarisation is strong, the method is unable to strongly constrain the degree
of polarisation beyond a systematics based estimation. Hence the implications
on GRB theory are unclear, and further measurements essential.
