The Gloucester-Class was an attempt to develop a more standardized 2Xs Heavy Cruiser (the 's' signifying normal, roughly medium 2nd-Generation X-Technology), with tests and the first few voyages of the USS Gloucestor Prototype under the command of Alexander Zephyr Radetsky, ending highly successfully.
However, the fielding of many other Heavy Cruiser Classes, chiefly the Redesignated Excelsior-Class in 2315, Excalibur Avenue, Philadelphia Beacon, Fontana, Solaris, Constellation, Podesti, and Dulane Classes, made it unnecessary to build more than three of these ships, the first two from 40 Eridani A in 2313, the third in 2327, all three easily maintained with spare parts and minor upgrades, and sent out hundreds of lys away for 20-30 year exploratory tours, some civilian researchers and families occasionally allowed on board for special occasions.

Ships Commissioned-

USS Gloucester, NCC-9833, Decommissioned 2387
USS Glastonbury, NCC-9834, Decommissioned 2386
USS Glounboucher, NCC-9835, Decommissioned 2385