It wasn`t profitable?
BHX is a regional airport having a smaller catchment area than to London. EDI is already served by both BA and fly be; satuation of a route with 3 carriers usually has one leaving it in this case the weaker was this airline. More paxs chose the latter airlines. BHX had BA, bmi and SN on the BRU route if you look now its served by just one now. However, before SN went bust bmi pulled off the route.