Each Naval fleet can compose of entirely different Battle groups, and even then each Battle group can be completely different for any other given Battle group.
The Mediterranean Fleet is currently under the Command of Hastings Yelverton, and as such he has structured it to match his combat ethics. He took command of the fleet in early 1869, and is still in the process of trying to get all of the Battle groups setup how he wants.
Yelverton, like many commanders of the era is still struggling how to best utilise the emerging Air force, this has limited his deployment of mixed Battle groups, but whether this will affect his ability to discharge his duty and protect the Empires holdings in the Mediterranean is yet to be seen.
His fleet currently consists of
6 Battle groups
2 Carrier Groups
2 Air wings
Each Battle group consists of
1 Battleship & Escorts
Carrier groups consist of:
2 Aircraft Carriers & Escorts
22 Wings of Fighters
Each Air wing Consists of
10 Wings of Fighters
In total the Mediterranean Fleet currently consists of
6 Battleships & Escorts
4 Aircraft Carriers & Escorts
84 Wings of Fighters
There are rumours within the fleet that at least one Dreadnought is en route to join the fleet itself, and at this time Yelverton will move his flag from the HMS Judgement to it. The fleet itself consists of ten Battle groups, three Carrier Groups and two Air wings. They currently patrol all of the Mediterranean from the base in Malta.
The Battle groups themselves are rarely all on active patrol at any time. This allows for Repairs, refits and shore leave, however as Yelverton always aim to keep at least half of his forces strength out on Patrolling.
Any Battle group that suffers losses is quickly brought into the Docks at Malta to repair, rearm and refuel. It is just as quickly replaced on Patrol by another full strength Battle group.
Only during extended periods of conflict will Yelverton allow his forces to be deployed understrength.
Rare is the occasion where Yelverton feels the need to venture out of his command compound, however he is a ferocious fighter and excellent tactician, whether he is in the thick of the action, or directing his forces over the wireless.
Yelverton has always been able to adapt to different situations and will move his Flag, from a Dreadnought to a Cruiser squadron if he feels this will give him the tactical advantage he needs.
While the threats from foreign nations continue against the British homeland, Yelverton is intent to hold his ground, and the land claimed in the name of Britannia until his orders tell him otherwise.