  We present polarisation observations of five pulsars whose profiles exhibit
two distinct emission regions separated by close to 180 degrees of longitude.
We fitted the position angle of the linear polarisation using the rotating
vector model and convincingly show that all the pulsars have the angle between
their magnetic and rotation axes close to 90 degrees. The simplest
interpretation of the results is that we see `main pulse' emission from one
pole and `interpulse' emission from the opposite pole. We have attempted to
produce emission maps of the magnetosphere above the polar caps for each pulsar
and find that the maps support the view that the emission region in pulsars is
complex, even when the profile appears simple. For three pulsars, we can derive
emission heights and polar maps which are consistent with emission regions
located symmetrically about the magnetic axis and confined to the open field
lines. For two pulsars, we find that either the emission arises from `closed'
field lines or that the profiles are highly asymmetric with respect to the
magnetic axis.
