I do love the Queen's English.
If I understand this correctly, cottaging refers to having sex in public toilets. Dogging also includes other public places and seems to imply a group effort that might involve both participants and observers. Cruising, exported from the States, threatens to make extinct these two words that are so much more quaint, comfy, whimsical, homey and gentle. They are not at all like that horrid British word, shagging that conjures synthetic fibers and the inevitable rug burns.
(Makes me want to have sex in a gingerbread dog house with green indoor/outdoor carpeting and a thatched roof.)
The interesting thing about British law governing this kind of adventuring is that it is illegal ONLY if someone sees it and reports it to the police. If a tree falls in the woods....
Or, "Don't See, Don't Know".
J'adore the Brits.