The nanny probably has no in intention of going back to work with her own baby though (probably pretty glad to get out having KH as her boss) and, yes will be claiming maternity pay, but if I remember correctly, and things haven't changed someone in KH's position can claim all the maternity pay (and a little bit more) back.
I bet her nanny would never contact a solicitor because she is a nice person, who just wants to get on with her life and having her own baby, and would like to send the DH's DC birthday cards without KH ripping them up.
Yes, the nanny was likely to have children at some point. To avoid this, you either employ a very young nanny, an older nanny, a male nanny or use a nursery.
DH used to run a small company, with excellent staff, all of whom were crucial to him. I can tell you he was not happy when one of his staff announced she was pg with her 2nd child (a bit inevitable with hind sight
). Yes, he could have spouted of KH style. His actual initial reaction was "How did that happen?" After that he realised it was best to keep his mouth shut.