Ron
You need to ensure they are imported under the correct UK Import Commodity code... that way you should only pay vat at most 5% and no duty.
Take a look here:
https://www.gov.uk/trade-tariff/sections
Make sure the sender clearly writes the code details on the outside of the package - ideally on the customs form.
You will still get Parcelfarce stiff you though for their "processing fee".
For WW2 vintage stuff, I use this one.
.
Section XXI - Works of art, collectors' pieces and antiques
97 - Works of art, collectors' pieces and antiques
05 - Collections and collectors' pieces of zoological, botanical, mineralogical, anatomical, historical, archaeological, palaeontological, ethnographic or numismatic interest
00 00 90 - Other
The commodity code for importing is 9705000090.
Importing from outside the EU is subject to a third country duty of 0.00 %.
Goods are subject to VAT reduced rate 5%.
Hope this helps in the future.
Tim