The Third Sea Lord had regular audiences with the monarch to report progress on warship construction. He also explained to the House of Lords and House of Commons what the Navy was buying, why it needed those ships, and how they would fit its future fleet. This gave the office political contacts that the Second Sea Lord's training responsibilities did not normally require. An admiral could then command the fleet he had helped build, as Jellicoe did before becoming First Sea Lord.
Notable Point · 37:18-39:51
Why Third Sea Lords often became First Sea Lords
Regular contact with ministers, Parliament, and the monarch made the materiel office an unusually strong apprenticeship for the Navy's senior professional post.