this is more or less a mixed flying roster that works to Scheme. Unless you have worked as Crew before you may not know about Scheme. Scheme is an official document that lays down the law about Cabin Crew and the limits on the duty they can perform.
Surely scheme or whatever it is called in BA is based around the CAA CAP371? That example roster doesn't include the requirement for 2 consecutive days off in 14 days, until day 27 in that example??