The MOD, as far as I am aware got a good deal from XL - the deal also includes the 747 flight to ASI and MPN.
These flights run to a usually good schedule - although delays have occurred, both partieshave been to blame sometimes :
Tech aircraft, late delivery of cargo, MOD employees damamging the 747 in MPN.
All the above will have an impact on max duty hours and scheduling - so, as i said, both parties to blame.
With regard to the BAH flights - the MOD originally had a 747 for these flights, however the MOD then wanted the 767 instead. The 767 operates a hefty charter program from the UK, and then positions to BZZ to operate the BAH.
Apparently the MOD are paying XL 30% less then what they paid Air Luxor.
Am not saying XL are exempt of blame - perhaps both parties are geting what they signed up for !