Why Jellicoe chose Iron Duke

Why did Admiral Jellicoe choose HMS Iron Duke as his flagship?

He knew the new class from his Third Sea Lord work, liked the ship, and valued her strong gunnery organization.

Jellicoe liked Iron Duke and did not change flagships without need. As Third Sea Lord, he had helped bring the class into service and knew the ships closely. Iron Duke also had one of the fleet's best gunnery officers, an important match for an admiral with demanding standards. The flagship choice combined personal familiarity with recent design responsibility and demonstrated gunnery competence.