Eventhough I am not from the Island , this is what I could find on British Airways site:
Carriage of Firearms and/or Ammunition
Restrictions and limitations
All firearms (including replica and decommissioned) and ammunition are restricted under UK law.
Ammunition (cartridges for weapons, small arms) in Division 1.4S (UN 0012 or UN 0014 only), must be securely packaged and in quantities not exceeding 5 kg (11 lb) gross weight per person for that person's own use, excluding ammunition with explosive or incendiary projectiles. Allowances for more than one passenger must not be combined into one or more packages.
Notify us before you fly
You must call one of our contact centres at least 72 hours before your flight if you intend to travel with firearms and/or ammunition. This is to ensure compliance with UK government (or other local government) embargoes and restrictions. Failure to comply with this notification requirement will result in refusal of carriage.
Notification must include:
Firearms
Quantity
Type (handgun, rifle, shotgun)
Make/model
Calibre
Ammunition
Quantity (weight) and calibre
Contact us
Travelling on British Airways flights operated by other airlines
If you are planning to make a booking on ba.com that includes a flight operated by an airline other than British Airways, please contact us before booking to check that the other airline is able to carry your firearm.
Please note: You will not be able to take any firearms, including sporting rifles, on any flights operated by Comair.
Documentation
All passengers intending to travel with firearms and/or ammunition must ensure they have the required documentation and licences for their firearms and ammunition. This includes export/import licences and authorisation from local and national authorities.
Check-in times
When you travel with firearms and/or ammunition you must be at check-in at least 2 hours before your flight, to allow sufficient time to process the paperwork prior to clearing security.
(Note: groups or individuals travelling with 10 or more firearms or boxes of ammunition must be at check-in at least 3 hours before their flight.)
Checking in at London Heathrow
To check in, proceed to the Assistance Desks located at the end of Zones B/C/D/F/G in Terminal 5 or in Zone G at Terminal 3. Customers in First, Club World and Club Europe should continue to use the respective First and Club check-in zones in Terminals 3 and 5.
Transferring through London
If you are transferring through London, you must allow a minimum connecting time of 3 hours between flights.
Handling Charge
Each case containing firearms and/or ammunition is subject to a ï½£50 each way charge at check-in. Firearms and ammunition are handled by a specialist third party agent on our behalf; this charge covers their costs.
Packing firearms
Firearms and/or ammunition will be accepted provided they are packed in an appropriate carriage case, or if this is not possible, packed securely inside a suitcase with your personal effects. If the firearm and/or ammunition is carried in addition to your free checked baggage allowance, extra bag charges will also apply.
Packing requirements for South Africa or Italy
Firearms and ammunition are not allowed in hold luggage with general personal possessions.
All firearms have to be packed separately from the ammunition and must be in a locked firearms case.
The ammunition must be separate and in its own locked bag/container.
In these instances you will not be charged for the extra bag(s) but will be subject to the appropriate handling fee(s).
Preparing firearms for travel
Each firearm carried must be accompanied by the appropriate firearms certificate.
The firearm must be unloaded.
There will be no additional cost for the carriage of ammunition packed with the firearm*.
Ammunition must be packed in either its original packaging or in a suitable container that prevents movement between shells or cartridges, i.e. loose ammunition is not permitted.
Bags with ammunition must not bear 'explosives' labels.
The Heavy Bag Charge will apply to all bags over 23kg.
*If ammunition is carried on its own without a firearm, the ï½£50 charge will still apply as special handling for the item is still required.
End of quote.
Usualy the Brits will find a way to make things more complicated than they are, at least this is what I experience when I go hunting in UK/ Scotland.
Regards BN