But the vendor might have!
From speaking to a number of traders, it seems that radio active items such as luminous instruments and compasses, etc are routinely intercepted at the point of departure.
First the vendor knows about it is an invitation to pop down to Heathrow to collect his property or pay the (huge) fee for them to dispose of it safely.
It all adds up to frustration, considerable cost and hassle, with ultimately, disappointment to you the buyer.
Avro turnbuckles aren’t radio active by the way! 🙂
I have’nt had a problem with customs etc, over luminous instruments. I sent a couple of them to NZ, along with various other bits, as part of the exchange deal I did, to get the fin & rudder etc for my Snipe.
Bob T.