Seat Preselection?
 

I will be taking my first circle fare this December (thanks to this site ;) ) booked ex-GIB through a very helpful agent (another FT recommendation!). I have been able to pre-allocate seats on all the BA flights through the EC but the agent is unable to help with allocations on QF and CX. Anybody know if it is possible to do this direct with the airlines on this type of ticket?

You should be able to pre-allocate seats on QF international flights (flight numbers QF1-QF399). If your agent won't do it, then call Qantas yourself. You cannot pre-allocate seats on QF domestic flights - this is done automatically based on FF status and preferences registed with the QF FF program.

The only limitation to pre-allocation on QF international services is that they will only pre-allocate up to a certain proportion of the economy cabin so allow for some last minute flexibility with families/groups at check-in time.

In my experience, I have been able to pre-allocate seats in CX economy class as well.

My experience has been that CX seats don't become eligible for preselection until 6 months prior to departure. Try again on the correct day this month and see if it works then.