Originally Posted by
KARFA
Yes I agree with MarkedMan. If you are sticking with the same dates you should be able to start from anywhere within 300 miles of DUB, and LHR would be within that. Or if you prefer you can start from somewhere in the UK (MAN, NCL, GLA,EDI etc.). There is no need to "rebook" the rest of the trip. BA will just need to re-ticket to reflect the change starting in LHR.
If you still want to start in DUB you can do so as well, so fine an alternative DUB-LHR flight which is running. There is no need to change any other flights in your booking unless the new DUB-LHR messes up the connection at LHR.
While that is usually the case, wont starting in the UK make the OP eligible for the APD? I suspect what has happened here is that the cancellation bots have been deployed, but the rebooking sweep has not occurred yet. OP - give the system 24 hours or so and you will probably find that your DUB-LHR leg has been reinstated. I've had similar happen to me with connections LBA-LHR and MAN-LHR, if the automatically rebooked segments are not convenient then call BA to ask for your options.