Chris Smith - "our man of great enthusiasm" - leads the Sussex Ramblers group which involves everyone with an interest in routes, (including: Mid Sussex Bridleways Group, Open Space Society, Ramblers, South Downs Society & Trail Riders Fellowship), that have not yet obtained Definitive Map status and so are not shown on any OS Maps yet. Maybe you have walked on them thinking they had Public Right of Way status. All the efforts to record historic paths was covered in a Walk magazine article; do read this article where Chris has quite a say on taking up the challenge.
If your interest is triggered by what Chris and the Sussex team are doing; there will be a lot to learn and enjoy in the friendly Ramblers group and then you would be ready to join in, to make a difference locally. Volunteers interested and already knowledgeable in local history could find an outlet for their interests. For example, we need to understand how landowners in the 1950s reacted to local authority officers asking questions about the land usage.