It is illegal to cycle on a public road after dark without lights and reflectors. Exactly which lights and reflectors, where to fit them and when to light up, is defined by the Road Vehicles Lighting Regulations.
Have you ever seen some pedal-powered contraption and thought: surely that isn't allowed on the road! If it has two brakes, it probably is, but here's where to find out for sure.
When you cycle into another country, your 'temporarily imported' bike doesn't have to be exactly like the bikes of that country, provided it conforms with a very basic, internationally agreed specification.
Standards are specifications for products and services. Usually they are voluntary, but they can always be referred to in deciding whether something is or was safe.
Cyclists' Touring Club (CTC): A company limited by guarantee, registered in England no.25185. Registered as a charity in England and Wales No 1147607 and in Scotland No SC042541
CTC Charitable Trust: A company limited by guarantee, registered in England no.5125969. Registered as a charity in England and Wales No 1104324 and Scotland No SC038626