]It is in Mr Shepherd's own interest that Sir Walter be solvent.

And this is not just in the short term; if Shepherd can get Sir Walter's finances back on track, Shepherd is securing not only Sir Walter's future, but also his own. It's a business relationship that can continue to bring in money as long as Sir Walter can afford Shepherd's services, so it is in Shepherd's best interests to see that Sir Walter will have business affairs in the future for Shepherd to manage indefinitely.