My mistake, rechecking the definitive map it is definitely showing that footpath so I have reverted the previous mapping. 

But what is the date on that ESRI image you found? I have to go back to *2016* at https://livingatlas.arcgis.com/wayback/#mapCenter=-0.19091%2C51.71435%2C18&mode=explore&active=6678 to see that footpath clearly. More recent versions (2017 to 2022) appear to show the path as planted over -- as was certainly the case in 2022 when I made the original post.