As I read this, unless you live together, it’s now unlawful to have sex with your lover indoors, but fine outdoors (subject to public decency offences); but you can have sex with an escort indoors, as that is reasonably necessary for their work purposes (see 7(d)(i)). https://twitter.com/adamwagner1/status/1267095533941919745

I’m not entirely certain that that result was intended.

And really, as Adam says, this device of publishing regulations governing every aspect of our lives at 14 hours notice is unacceptable. And not getting a Parliamentary vote is now very likely unlawful: no plausible argument for urgency. See https://www.prospectmagazine.co.uk/politics/george-peretz-lockdown-regulations-parliament-scrutiny-law

One point made to me is that the “work purposes” exemption in 7(d)(i) may apply only where everyone in the gathering is participating for work purposes (so would not cover an “encounter” with an escort, where the client is not usually participating for work purposes).

But that doesn’t work with the 2nd limb of the subparagraph (provision of voluntary/charitable services) - typically, the gatherings covered will be ones where some are there to provide and some are there to receive (a volunteer going round to a lonely person’s house for a chat).

And note that if you apply that interpretation the para would not cover a solicitor going to someone’s house to take instructions on (for example) a will or a power of attorney - a form of social interaction - (NB there may be very good reasons for not doing that by Zoom).

But what all this shows is that you need scrutiny for all this stuff. Scrutiny throws up uncertainties and oddities of this kind and means that they get dealt with.

Another good point made to me - 7(2)(b) says that a person may participate in an oversize gathering if he is attending a funeral as a household member/relative/friend of the deceased. But that doesn’t seem to cover the priest.