  We rediscuss the evolutionary state of upper main sequence magnetic stars
using a sample of Ap and Bp stars with accurate Hipparcos parallaxes and
definitely determined longitudinal magnetic fields. FORS1 at the VLT in
spectropolarimetric mode has been used to carry out a systematic search for
magnetic fields in chemically peculiar stars whose magnetic field has never
been studied before. We confirm our previous results obtained from the study of
Ap and Bp stars with accurate measurements of the mean magnetic field modulus
and mean quadratic magnetic fields that the distribution of the magnetic stars
of mass below 3 M_o differs significantly from that of normal stars in the same
temperature range. Normal A stars occupy the whole width of the main sequence,
without a gap, whereas magnetic stars are concentrated towards the centre of
the main-sequence band. We show that, in contrast, higher mass magnetic Bp
stars may well occupy the whole main-sequence width.
