Whilst it is not a legal requirement to have reflectors in the daylight, the minute the darkness descends then cycles are supposed to have reflectors to the front and rear and also on their pedals. So whilst most bikes are sold with them, most (especially those of the racing variety!) discard them very quickly. There is one dispensation though - if your bicycle was originally manufactured before October 1985 then you're exempt from pedal reflectors. Check the Bicycle Lighting Regulations for more detail.