Hi Pandy
Just spoke to BA here at BRS and in their system it is showing that you can book EDI-BRS-ZRH as a through ticket with a 50 min connection, I was told there maybe a computer problem on the net booking system.
Give them a call on 08708509850.
(This is not an advertisement I will list all of the numbers of the airlines at BRS if the mods want me to)
hope this helps
T21