The only two places mentioned by the article as venues for the unwrapping of mummies are the Royal College of Surgeons and an anthropology museum.
This makes me think that the headline of the article is slightly misleading, as it makes one think of mummies being unveiled after dinner parties in houses across England. The article even says that the 'parties' are restricted to the scientific community. Despite there being audiences for these events, it does seem that the unwrapping of mummies was less frivolous as the article may suggest.
I've read about these in books. There isn't a ton of documentation on the private parties because they were kind of illegal and the British are kind of embarassed about it. The intent was, oh well have an unwrapping party and it'll be a jolly good time. Then we'll give the mummy to museum. It's just a detour on it's way to the museum. Really we're doing them a favor by unwrapping it for them. But of course they were pawing at them and most of the mummies didn't survive their groping.
There's a pretty cool Edgar Allan Poe short story called some words with a mummy where somebody hooks a battery up to a mummy at a unwrapping party and it comes back to life and beats the shit out of them.