unless I have got this wrong there isn't 11 hours between shifts so that wouild be illegal
That doesnt apply to all occupations.
http://www.direct.gov.uk/en/Employment/Employees/WorkingHoursAndTimeOff/DG_10029451
However, I wouldnt take on a job that was 15 and a half hours a day, thats too much, I used to do near that at ANC, I would be in at 0600, and sometimes wouldnt be home till 2130.