  The current value of Vud is determined from superallowed beta-decay
experiments. Other methods, briefly summarised here, have to overcome specific
experimental hurdles before they are competitive. However, the nuclear results
do depend on a nuclear-structure calculation of isospin-symmetry breaking,
which is often a cause of some concern. We show here, by adopting the Conserved
Vector Current (CVC) hypothesis, that these theoretical corrections can be
tested for consistency. In this test, calculations based on the shell model
with Saxon-Woods radial functions perform the best.
