I always wonder what people like maypole think would be the ideal. No women in the workforce? A one child only policy? Or for women to give up work the moment they (and their partners) decide to try to start a family a la 1950s?
Obviously all people who are half-awake already know this, but for the benefit of the others, let's just remind ourselves that employers can claim back all the costs of SMP from the government so this "by the time you add up maternity pay" nonsense is irrelevant.
Employers also generally get considerably more notice from a woman going on Mat Leave than from someone leaving to get another job. And once a woman has children, she is more likely to be loyal to her employers than before, given that she has to work around the logistics of childcare etc, so that leaving one secure job for a the unknown terms of another is a far more serious proposition than before.
Anyway, as iggi said, the behaviour of this employer sounds straightforwardly illegal, so I'm not sure why it merited a debate on national TV.