  We present a detailed analysis of the radio galaxy PKS 2250-351, a giant of
1.2 Mpc projected size, its host galaxy, and its environment. We use radio data
from the Murchison Widefield Array, the upgraded Giant Metre-wavelength Radio
Telescope, the Australian Square Kilometre Array Pathfinder, and the Australia
Telescope Compact Array to model the jet power and age. Optical and infra-red
data come from the Galaxy And Mass Assembly (GAMA) survey and provide
information on the host galaxy and environment. GAMA spectroscopy confirms that
PKS 2250-351 lies at z=0.2115 in the irregular, and likely unrelaxed, cluster
Abell 3936. We find its host is a massive, `red and dead' elliptical galaxy
with negligible star formation but with a highly obscured active galactic
nucleus dominating the mid-infrared emission. Assuming it lies on the local
M-sigma relation it has an Eddington accretion rate of lambda_EDD~0.014. We
find that the lobe-derived jet power (a time-averaged measure) is an order of
magnitude greater than the hotspot-derived jet power (an instantaneous
measure). We propose that over the lifetime of the observed radio emission
(~300 Myr) the accretion has switched from an inefficient advection dominated
mode to a thin-disc efficient mode, consistent with the decrease in jet power.
We also suggest that the asymmetric radio morphology is due to its environment,
with the host of PKS 2250-351 lying to the west of the densest concentration of
galaxies in Abell 3936.
