The first one is priority to someone with a broken arm (or any bandaged part I guess). Second one priority for people with young kids. Third, priority for pregnant women. I can't for life of me remember what last one is tho, sorry.
They're doctored obv, or am i getting whooshed? Having just returned from japan, they are for pregnant woman, one is of a person holding a crutch, one is for someone disabled and one for carrying children i think. Can;'t quite remeber - they're similar to ours ie give up this seat or those seats that are reserved for pregnant/disabled/injured whatever, but i defeinitely would have remembered seeing those signs!
I think these signs first appeared on London Underground's Central Line, warning late night travellers not to have sex in the tube train, as, in the event of pregnancy, they could not guarantee that the train would reach Ealing Broadway before the child was born.