On the pavements outside well-off Victorian houses you often find theses round metal shapes - they are covering holes, trought which Victorian households had their coal delivered.
Victorian families in this area burnt coal in fires to heat their houses and ovens (it was before central heating!). Rather than dragging dirty coal sacks through people's homes, the coalmen used to drop it from their horse-drawn carts through this hatch straight into the cellar.
Scullery maids would the move the coal from the cellar to the fires and clean the house of all the dust created by burning coal (a very hard job!)
The hatch is typically about 12 to 14 inches (30 to 35 cm) in diameter and consists of a cast iron ring set into the pavement, with a circular cover, often made of cast iron alone but sometimes containing concrete or glass panes or small ventilation holes. There are three main reasons for the circular shape of the coal hole plate: a circular disc can not accidentally fall through its own hole (unlike a square or rectangular one); its weight means that it can be rolled rather than carried or lifted; and the absence of corners allows for a reduced risk of damage to it. Hatches have an internal latch that prevents the cover being lifted from the outside. On some streets there are a variety of types of cover reflecting the fact that the coal holes were installed at different times by different builders after the houses were built.