"They live in towns and villages well inland from the coast having moved there because of what at the time was a daily GRX-LGW service operated by Monarch."
I'm sure there are other factors at play but I find it strange that people would choose to move to and invest in a property based on the availability of a single flight back to the UK from a nearby airport. Surely if convenience of having a flight back to the UK is the sole and prime concern, one would locate near a bigger airport (in this case AGP) that offers a better range of flights to the UK so that if your chosen route is pulled there is more likely another that you could use in its place without then having to travel a distance to a different departure airport.
Having said that, Granada is a fine and lovely city and in this case I can see SOU-GRX as an possible route for BE, as well as BHX-GRX although whether these would suitable for year round ops is debatable.