Hopefully the reality of how the seniority system works at BA cannot be a surprise to any one sitting in the hold pool who performed due diligence.
I know it's been said before but here it is again: like it or not pretty much everything in BA is governed by date of joining....you must assume the pilot who joined a day/week/month ahead of you will get first shot at a command course unless there's a very rare combination of circumstance. In the 90s and later the likes of the Prestwick Cadets got commands ahead of DEPs who had joined from the forces/other airlines, and unless the rules change you can expect the FPPs and the possible "white tales" to get a shot at command ahead of any high hours LHSeaters joining from FR, Emirates or wherever.