A thought, HMG was embarassed into creating the OSA as other nations rewarded their personnel for arduous operational service. Quite right too that this was recognised as there will be many ineligible for the current operational tours.
The money has to come from somewhere and LOA is an easy target as it is not usually arduous service but was 'clearly' being compensated at a greater rate than operational service. To the uninformed this would seem an easy comparison and thus an easy hit.