Rear admiral is a flag officer rank of the Royal Navy. It is immediately superior to commodore and is subordinate to vice admiral. It is a two-star rank and has a NATO ranking code of OF-7.
World War II Royal Navy rear admiral's steel helmet with two-star insignia
These are the official Royal Navy Officer ranks ordered by rank. These ranks are now part of the NATO/United Kingdom ranks, including modern and past.
Rear admiral (Royal Navy)
…Rear-Admiral of the Red Royal Navy officer rank insignia List of Royal Navy rear admirals…
Royal Navy epaulettes for senior and junior officers, 18th and 19th centuries
Royal Navy epaulettes for flag officers, 18th and 19th centuries
An example of a Royal Navy officer of the lieutenant rank – Lieutenant Carre Tupper, 1814