JRM Dubrovnik, a large destroyer design built as a flotilla leader
A flotilla leader was a warship suitable for commanding a flotilla of destroyers or other small warships, typically a small cruiser or a large destroyer (known as a destroyer leader). The flotilla leader provided space, equipment and staff for the flotilla commodore (who typically held the rank of captain), including a wireless room, senior engineering and gunnery officers, and administrative staff to support the officers. They were a feature of navies in the late 19th century and early 20th century. Originally, older light or scout cruisers were often used, but in the early 1900s, the rapidly increasing speed of new destroyer designs meant that such vessels could no longer keep pace with their charges. Accordingly, large destroyer designs were produced for use as leaders.
As destroyers changed from specialized anti-torpedo boat vessels that operated in squadrons to larger multi-purpose ships that operated alone or as leaders of groups of smaller vessels, and as command and control techniques improved (and the technology became more readily available), the need for specialized flotilla leaders decreased and their functions were adopted by all destroyers. The last specialized flotilla leader to be built for the Royal Navy was HMS Inglefield, launched in 1936. Subsequent leaders used the same design as the private ships of the class, with minor detailed changes to suit them to their role. In the Royal Navy, the flotilla leader and commanding officer were known as Captain (D). In the Royal Navy, flotilla leaders and divisional leaders could be identified by particular coloured bands painted on their funnels.