as long as you tell them :
24. Can I take my shotgun, rifle or weapon with me in the car?
Yes, provided you are fully licensed and can fulfil all the legal requirements.
You must declare this at the time of booking by phoning our Contact Centre at least 24 hours before you intend to travel:
Telephone
Call centre: 0871 574 7223, or
Call centre (outside UK): +44 (0) 208 127 8303
You can take ammunition, but this must be kept to a minimum and wherever possible, stored separately from any weapon, e.g. in another compartment.
The weapons(s) must remain inside the vehicle and wherever practicable, the bolt, magazine or other vital operating part should be separated from the gun and either carried on the person, secured or hidden in the vehicle, or kept in a locked container, ideally secured to the vehicle. Any weapon must also be obscured from view, under a cover or inside a container. Once onboard, the ships loading officer will be discretely aware of you and will ask you to surrender your car keys for the duration of the crossing. The vehicle must remain locked and alarmed, if fitted. On arrival, the keys will be given back to you.
Once you have informed us of all the details, we must pass the information to other interested parties. All vehicles are subject to searching at both ports and this will avoid any misunderstanding. However, you should still discretely confirm to the check in operator that you are carrying such.
Even if your gun is only for display, the requirements are exactly the same.