Who is Sir Leslie Hewitt from Dead in the Water: A Novel and what is their importance?

Sir Leslie Hewitt is the barrister that Stone hires to help represent Allison in the St. Marks court. Stone cannot represent Allison directly because he is not a member of the St. Marks bar. However, Sir Leslie was only supposed to represent Allison long enough for them to bring in a barrister from England. Sir Leslie supposedly has senility problems and forgets to stipulate this part in court. In this way, Sir Leslie becomes Allison's lead defense attorney.