You sure you'll miss it ? ... Looks like BA1315 is only 45 mins late .. so with a bit of luck maybe only half an hour late into Heathrow which would still give you well over an hour , nearly 90 mins with a bit of luck ... It's the last flight of the night to Doha so you may as well give it a shot and not give up hope yet ? I'd say you've got a reasonable chance ?