Yes, you should be seething. Apparently it is the thing for young people not to bother to acknowledge gifts, wedding presents, baby gifts. My daughter was very surprised, and pleased, to receive thank-you letters from some of her friends recently; no-one had bothered before.
I too, was pleased to receive thank you cards with pictures of the newborn for very small gifts to children of daughter's friends and girls I used to work with.
Recommendations please for thorn- and nettle-proof gauntlets – if possible vegan


