Have you thought about re-applying now that the revised Home Office Guidance is fully in force and constabularies are being directed by FELWG to align their firearms licencing administration with it?
Even though I have other 'suitable' rifles for UK boar and deer I was able to make a case for the 9.3x62, (primary good reason is use abroad), and expanding in the UK based mainly around sections 13.36, 13.37 and 13.9 of the Guidance, plus the necessity of being able to develop, zero and practice with expanding loads that would provide a humane outcome on any quarry species irrespective of where in the world they happened to be. It is becoming increasingly difficult for any FLD to refuse expanding in this type of scenario, as they are then leaving themselves open to criticism on animal welfare grounds - they just need the facts pointing out to them.
If you want a copy of arguments I put forward PM me with an email addy that will accept attachments.