Airfix must have believed there was a market for this mark in 1/48 even when there was already a kit in this scale available from another manufacturer so why not in 1/72?
There is a conversion kit available from, I believe, 3D Kits, it includes the prop, spinner, and starter bulge, two of each in each kit, they can be found on E-Bay.
The 1/48 scale Spitfire Mk.XII and Mk.XVIII kits are good kits, is there any chance Airfix might consider scaling them down to 1/72, at the moment these are two marks that have virtually no representation in this scale and leave a gap in the market that might be worth filling.