  We announce the discovery of an extended emission line region associated with
a high redshift type-2 QSO. The halo, which was discovered in our new
wide-field narrow-band survey, resides at z = 2.85 in the Spitzer First Look
Survey region and is extended over ~80 kpc. Deep VLBI observations imply that
approximately 50 per cent of the radio emission is extended on scales > 200pc.
The inferred AGN luminosity is sufficient to ionize the extended halo, and the
optical emission is consistent with being triggered coevally with the radio
source. The Lyman-alpha halo is as luminous as those found around high redshift
radio galaxies, however the active nucleus is several orders of magnitude less
luminous at radio wavelengths than those FRIIs more commonly associated with
extended emission line regions. AMS05 appears to be a high-redshift analogue to
the radio-quiet quasar E1821+643 which is core dominated but which also
exhibits extended FRI-like structure and contains an optically powerful AGN. We
also find evidence for more quiescent kinematics in the Lyman-alpha emission
line in the outer regions of the halo, reminiscent of the haloes around the
more powerful FRIIs. The optical to mid-infrared SED is well described by a
combination of an obscured QSO (L_bol ~3.4 +/- 0.2 x 10^13 Lsolar) and a 1.4
Gyr old simple stellar population with mass ~3.9 +/- 0.3 x 10^11 Msolar.
