Where's the path is a great little site that allows you to display all sorts of maps including the OS 1:25K maps with rights of way. Unlike the OS Get A Map service you can display and print larger map sections without an account.
Oxfordshire County Council maintain the 'definitive map' for the county that includes all rights of way, so they should really know where the paths are. In a welcome move they have now put up an online Countryside Access Map that includes all rights of way and access land including permissive paths that may be missing from OS maps. The interface is a bit clunky for planning hashes but it can be useful to check for areas that can be 'roamed' over more freely than indicated on the older OS maps (or by 'keep out' signs left about to put you off).
Here is an example - Clifton Heath near Clifton Hampden....
Since publishing this page we have been contacted by Barry Cornelius who has pointed out that the Council now also have the Definitive Map of paths online in PDF files. The map gives you access to all 142 PDF files that cover the whole of Oxfordshire. They are high quality and you can zoom right in.
Barry is undertaking a project to walk or run all the paths of Oxfordshire and to provide web pages documenting the paths. Barry do you fancy joining the hash by any chance!
To make it easier to navigate Barry has kindly provided a page that enables you to search the map collection for a specific place, so you can use his page to find the PDF file that covers the area you are laying a trail - brilliant. As they are PDF files you can download them and print out the sections you need for personal use.
Check out Barry's Definitive Map Search. Thanks Barry!