H Laura
Welcome to the forum, most inner city roads had back court or back terraces. Which were houses that ran off the main street, sometimes accessed by narrow covered enteries, sometimes the access was wider. As a rule the back courts were given names but sometimes the were given numbers. Mostly thet were referred to as a court number depending on how many there were and the house number of the street fronting house. Hence number 8 house behind street number 140 became 8/140.