I have a handbag highchair - very useful. Drawbacks are, it doesn't fit on chairs with arms or with very tall backs and obviously doesn't have a tray so the chair can get messy. We used it on holiday though and were happy with it, also good at home to keep in the changing back and use when eating out.
Yes,they are rather like hankies. I therefore presume that the reason ours disappeared is that some big drunken bloater mistook it for one and took it home in his pocket. Hmmmmmmmmm. Most annoying as I did really like it.
(Hello MI, btw. Hope the party went well. Ours did......)
I've just found it and put it in a padded envelope. It's quite easy to use but you may want to ring me to talk through how to put it together. If you don't use it on holiday, you may use it another time.