Battlecruiser fighter rails versus carriers

Would battlecruisers with fighter-launching rails provide useful emergency CAP for convoy escort or carrier vulnerability windows?

The Royal Navy would meet that need with carriers, old battleships on convoy duty, and multi-carrier operations. Fighter rails would add aviation hazards and recovery problems to new battlecruisers.

British carrier practice makes fighter rails an unnecessary complication. Hermes, Argus, Eagle, escort carriers, and cruiser carriers were the more natural convoy and sea-control tools, while old battleships would take many capital-ship escort assignments. Rail-launched fighters would still need recovery arrangements and would bring aviation fuel and fire hazards aboard the battlecruiser. British perpetual operations and multi-carrier doctrine were designed to maintain fighter cover while strikes were launched.