You MUST NOT
carry a passenger unless your cycle has been built or adapted to carry one
https://www.gov.uk/guidance/the-highway ... s-59-to-82
24 Restriction of carriage of persons on bicycles.
(1) Not more than one person may be carried on a road on a bicycle not propelled by mechanical power unless it is constructed or adapted for the carriage of more than one person.
(2) In this section—
(a)references to a person carried on a bicycle include references to a person riding the bicycle, and
(b) “road” includes bridleway.
(3) If a person is carried on a bicycle in contravention of subsection (1) above, each of the persons carried is guilty of an offence.
One point there is that in this country you would both have been nicked.
On a lighter note, I mentioned on another thread that the late Ken Dodd reported having been nicked for giving a lady a croggy on her own bike.
I've found these about Germany which both look useful in their different ways. The first looks pretty informative to me in PDF form and is from an official source.
http://www.germanroadsafety.de/download ... and_en.pdf
The second seems to look at it from a visitor's perspective, but that's an American visitor. The author admits to not being a fluent speaker of German and has used google translation but their English is unusual and probably just as unusual to AmE speakers.
eg "Bell / horn: For dispensing acoustic warning."