I had a very similar discussion with a couple of RFD's when I was buying a rifle (but not a person to person transfer).
The rifle could not be shipped to me as a 'private individual'. (can only be shipped RFD to RFD)
I was awaiting the grant of an additional 'slot' on my FAC
I (obviously) had to pay for the rifle before the RFD would ship it to my local RFD
It was then pointed out that after I had paid for it , I owned a firearm for which I did not have a licence - technically illegal
If you own a rifle then you must be licensed for it.
As it happened (and apparently a common 'loop-hole') the rifle is shipped to the other RFD, but is not shown as being sold until the grant of the variation and the rifle collected from the receiving RFD
Any person wishing to possess, purchase or acquire any firearm or ammunition must hold
a valid firearm or shotgun certificate (as appropriate) unless exempt under sections 7 to 13,
15, 54 or 58(1) of the 1968 Act or sections 15 to 19 of the 1988 Act,