Quote from CAP 371 - You'll need to check your company's approved FTL scheme, for the definitive version.
"24.2 The limitations which shall be applied to cabin crew are those applicable to flight crew members contained in paragraphs 6 to 23, but with the following differences:
a) A flying duty period can be 1 hour longer than that permitted for flight crew. The FDP and limits set on early starts for cabin crew shall be based on the time at which the flight crew report for their flying duty period, but that FDP will start at the report time of the cabin crew."
The maximum FDP, for a duty of 4 sectors with an 0555L report is 10 hours for cabin crew, 9 hours for flightdeck. I can't see where you get 11 hours from, (a split duty wouldn't cover it either).
Assuming the flightdeck reported at 0625L, then your maximum FDP would have been 11 hours 45 mins, but your duty would have started at 0555L. In otherwords you had hours until 1740L, 0555 + 1145 = 1740.
The reason this is not used after days off, is because you would have been on duty prior to 0600L and hence infringing the local night, which in turn invalidates the day off.