It only seems to exist for a couple of years. It appears in Kellys in 1879 with Frederick Mitchell the master (not there 1878), is listed 1880 with Frank mitchell the maser, but has gone by 1882. However the master, Frank mitchell appears in 1882 as the master at a "Test house" in Lansdowne st (which was not listed before), under the auspices of the union. So it looks as it the test house may have replaced the branch workhouse. but I've no idea what a "Test house" is.
mike