According to this article https://www.theguardian.com/uk-news/video/2018/jun/15/upskirting-happened-to-me-and-now-im-changing-the-law-video "upskirting" is not illegal in the UK. That sounds unbelievable in my ears. Can someone confirm this claim? Also, why isn't this considered sexual assault or something like that? Taking of someone's clothes in a sexual way, without the camera, must be a crime, mustn't it? So why is it not a crime to take a photo of the "act"?
It is illegal in Scotland. There is currently no law specifically against it in the rest of the UK. If you find this is unbelievable, yes it is. There are attempts now to change the laws.
PS. There are no photos taken "of the act". Taking the photo is the act. The pervs use a selfy stick or just get down on the floor to take photos, or take photos on stairs.
PPS. News on Jan 16th 2019: "A new law will now be introduced in the next couple of months. It could mean that perpetrators might face up to two years in prison and are added to the sex offenders register."
I believe it isn't illegal but it would fall under "Anti-social behaviour" which is a civil tort defined by the Anti-social Behaviour Policing and Crime Act 2014.