  In this paper we present new observations of the gravitational lens system
JVAS B0218+357 made with a global VLBI network at a frequency of 8.4 GHz. Our
maps have an rms noise of 30 microJy/beam and with these we have been able to
image much of the extended structure of the radio jet in both the A and B
images at high resolution (~1 mas). The main use of these maps will be to
enable us to further constrain the lens model for the purposes of H0
determination. We are able to identify several sub-components common to both
images with the expected parity reversal, including one which we identify as a
counter-jet. We have not been successful in detecting either the core of the
lensing galaxy or a third image. Using a model of the lensing galaxy we have
back-projected both of the images to the source plane and find that they agree
well. However, there are small, but significant, differences which we suggest
may arise from multi-path scattering in the ISM of the lensing galaxy. We also
find an exponent of the radial mass distribution of approximately 1.04, in
agreement with lens modelling of published 15-GHz VLBI data. Polarisation maps
of each image are presented which show that the distributions of polarisation
across images A and B are different. We suggest that this results from Faraday
rotation and associated depolarisation in the lensing galaxy.
