How RNLI networks helped organize the Dunkirk evacuation

How important were the Royal Navy and RNLI to the evacuation from Dunkirk?

Very important, especially because RNLI people and existing small-boat networks supplied organization as well as vessels.

The lifeboat service genuinely turned up for the evacuation. Many private-boat crews also came from RNLI or yachting circles and already knew one another. Those relationships reduced the need to invent a command structure on the spot and helped direct vessels through difficult waters. Pre-war civil maritime institutions thus became operational capacity during a military emergency.