  Data are presented from the DRIFT-IId detector housed in the Boulby mine in
northeast England. A 0.8 m^3 fiducial volume, containing partial pressures of
30 Torr CS2 and 10 Torr CF4, was exposed for a duration of 47.4 live-time days
with sufficient passive shielding to provide a neutron free environment within
the detector. The nuclear recoil events seen are consistent with a remaining
low level background from the decay of progeny of radon daughters attached to
the central cathode of the detector. However, energy depositions from such
events must drift across the entire width of the detector, and thus display
large diffusion upon reaching the readout planes of the device. Exploiting this
feature, it is shown to be possible to reject energy depositions from these
radon decay progeny events while still retaining sensitivity to nuclear recoil
events. The response of the detector is then interpreted, using the F nuclei
content of the gas, in terms of sensitivity to proton spin-dependent
WIMP-nucleon interactions, displaying a minimum in sensitivity cross section at
0.5 pb for a WIMP mass of 100 GeV/c^2.
