We would need to look at CAA figures if they were published for the route.
I doubt they would have increased the service to daily if it wasn't needed. I think the fact they rerouted the flight to EDI and laid on buses too shows there was enough demand. They could have just refunded everyone months ago and left them to find their own way.
I only personally flew the route once and on both legs it was full, that was 2 months in.