Anti-ice is exaggerating a touch methinks.
With post duty-clear times of up to an hour and a half and rest periods of 15 and a half hours if you do a long day (I think 12 hrs gives you 15 off) it is virtually impossible for LHR SH CC to do 50-60 hours (bit of a difference there too) of work in 6-7 (?) days without agreeing to it.
Minimum turnaround at LHR? 2:30, any less and it's a CAT with £37. Less than 2hrs and you go home or delay the flight, unless night stopping then you can go down to 1:30.
My other half is LHR SH CC, she does some long days but gets good rest periods between trips, and on a typical long day (other than a band 4) will have a long break in the middle. 12:30 duty for a MAN and back then up to NCL? Hardly back breaking is it?
WW is not stupid, he knows he can't walk all over BALPA when it comes to bidline/crew complements/hotels. BALPA is a union consisting mainly (not entirely) of fairly selfish people who didn't care about the FSS for new entrants or even the AMP much until it affects them, but you try to take away something major; already in place which will directly negatively affect the whole workforce, and you're asking for big big trouble.