My son and his family live in the US and I share your woes about the mail. To be honest, so many things I've sent have gone missing that I think I'd be reluctant to send anything precious such as you want to do.
Will either they or you be visiting one another soon? Or as Grannykmot suggests, do you know anyone travelling to the US or do they know anyone coming over to the UK who could transport them?
I regularly send packages via Royal Mail to the USA. Up to 2kg for approx £22. Its amazing how adept I've become at finding lightweight gifts.
This is different. I want to send 4 walking sticks to my ds in the USA. They belonged to my df. There is no monetary value, just well used and well loved. Two of them he made himself. Wrapped up they weigh 1.7kg. But..... as you can imagine they make a long narrow package and this package shape has to go by Parcelforce rather than Royal Mail.
Parcelforce assesses on " volumetric weight" as well as actual weight, which ever is the greater. To send by Parcelforce Value or Economy the cost is around £75 !!
DHL also will charge around £70.
I'll go to the Post Office tomorrow but I've been through the web site and it seems this volumetric weight is about 4.5kg. (as opposed to the actual weight of 1.7kg. I'm gutted. It seems such a lot of money. Even if it was just one walking stick it would cost much the same .... because of the shape.
I'll probably go ahead and post these regardless of cost because I'd like my son to have them, ds would like them, and my df would be so happy to know that they went to ds. My father died before he saw my ds achieve his P.hd and never saw him get married and never saw his ggc.
Don't know what I want really, just venting. So disappointed at the cost.