  We re-discuss 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. 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
magnetic stars of mass M < 3 M_sun are concentrated towards the centre of the
main-sequence band. In contrast, stars with masses M > 3 M_sun seem to be
concentrated closer to the ZAMS. The study of a few known members of nearby
open clusters with accurate Hipparcos parallaxes confirms these conclusions.
Stronger magnetic fields tend to be found in hotter, younger and more massive
stars, as well as in stars with shorter rotation periods. No evidence is found
for any loss of angular momentum during the main-sequence life. The magnetic
flux remains constant over the stellar life time on the main sequence. An
excess of stars with large obliquities beta is detected in both higher and
lower mass stars. The obliquity angle distribution as inferred from the
distribution of r-values appears random at the time magnetic stars become
observable on the H-R diagram. After quite a short time spent on the main
sequence, the obliquity angle beta tends to reach values close to either 90 deg
or 0 deg for M < 3 M_sun. The evolution of the obliquity angle beta seems to be
somewhat different for low and high mass stars. While we find a strong hint for
an increase of beta with the elapsed time on the main sequence for stars with M
> 3 M_sun, no similar trend is found for stars with M < 3 M_sun. However, the
predominance of high values of beta at advanced ages in these stars is notable.
