Wain Wood is an ancient woodland extending to 19.2 hectares (47 acres) near Preston in North Hertfordshire.

[3] Wain Wood is situated on a north-east facing slope over decalcified boulder clay.

It is an example of a habitat with limited and localised distribution in the United Kingdom due to deforestation or afforestation, especially with conifers.

The author and Baptist preacher John Bunyan preached in Wain Wood.

Up to the 1880s, anniversary services were held in the wood to commemorate Bunyan's preaching.