Last time I looked, there were roughly 10 Admirals and RM Generals to directly lead the 'core' naval service of some 30,000 people, of whom 6 sit on the Admiralty board.
In rough terms thats the head of the RN (1SL), the head of the Fleet (generates the warships and deploys them), the head of the Naval Personnel and training side (2SL).
There is then a small number of supporting 2* posts linked to heading up specific areas where you need for various good reasons a senior officer. Most of these 2* posts are double or triple hatted - in other words, the incumbent gets to do three jobs that twenty years ago would usually have each had one person doing them full time. For instance the current Naval Secretary is the personnel manager for the RN, senior officer for Scotland/NI, and also the senior 2* to lead the Reserves.
The remaining 20 or so posts are for 'purple' jobs outside of the RN, but where the RN has an interest in filling them, for instance Chief of Defence Intelligence or some NATO posts.
Having had some exposure to these Admirals and other seniors, I'd say this. They work VERY hard, they get very few perks, their days start early and finish late, and they earn a fraction of what they could earn for posts with similar responsiblities in civvy street. They also exist from one job to the next, and if their post finishes and no suitable role exists, they are out of the service - something that happens a lot.
Frankly I find these tired arguments about Admirals pathetic. The total 2* and above plot for the Naval Service is roughly 0.1% of its total manpower, yet we act as if this is somehow a bad thing. More widely the total RN manpower figure for all OF5 and above still only comes in at roughly 350 people (so rougly 1% of naval manning or 350 people). Add in all the SO1s and you go up to roughly 1500 people, or 5% of Naval Service manning for all Commanders and above.
There are very few multi-billion pound industries out there withtens of thousands of employees, with such a tight top level of management. To add to this, there is a constant pressure to identify savings and reduce posts further.