Hi LB,
Not quite! BA pilots are rostered to Bidline limits which, as with the cabin crew, are our industrial agreement. The same negotiation is required to amend BLRs as would be for the CC industrial flight time limitations to be amended. That some pilots elect to work beyond BLRs on the day in an attempt to complete the flight is outwith the industrial framework that BLRs themselves represent. Indeed, many CC operate into discretion quite frequently which represents work beyond the industrial framework.
Cheers
MrB