Infact one wrote a letter to BALPA to express exactly that, and to ask why the GSS FOs are still being treated so abysmally.
Do you have a date for that letter? The only one similar in the Log I remember was from a retired BA 747 skipper who was working for GSS, no doubt for peanuts to supplement his 6 figure crystallised pension.
GSS may one day walk away from BA as a customer (or at least take on others) - Other customers ARE being actively sought; Then you know where you can stick your secondments.
GSS exists
solely to serve BA World Cargo. Perhaps other customers will be found in due course, but how long will it take to get four or five 744Fs worth to replace BAWCs work? If GSS walk away then thats no bad thing for BA pilots. The work would have to be taken in house so there'd be no need for secondments, they'd all be bona fide BA jobs.