  We present polarisation observations of the gravitational lens system
B1422+231 made at 8.4 GHz using the VLBA and the 100m telescope at Effelsberg.
All four images of the quasar show structure on the milliarcsec scale. The
three bright images show tangential stretching as expected from lens models.
Some basic properties of gravitational lensing are exhibited by this system.
The surface brightness of images A and B are the same and the parity reversal
expected in image B is revealed, for the first time, by polarisation
observations. There is a large differential Faraday rotation between images A
and B.
