Don't know about the LBA situation specifically but I believe SIDs, STARs and other instrument flight procedures are currently designed by the CAA's Directorate of Airspace Policy. No doubt the designs are developed in conjunction with the airport users and ATC.
Things may be changing though. There's consultation going on at the moment on a plan to transfer responsibility for designing approach procedures to the airport (or consultants) and the CAA will just approve the design. And on the topic of consultation, the CAA consults on proposed changes to airspace (which are done by the same Department of the CAA) but I don't know whether SIDs and the like get the same airing before they are implemented.
The SID naming convention is quite straightforward (in ICAO PANS-ATM or PANS-OPS as I recall) and the numbers are incremented when the procedure is amended for any reason.