Site visit July 21 2020. indicates that this is not a public bridleway.
 A couple of signs on this path say "The public are permitted to use this path on foot only for access to the Duryard Valley Local Nature Reserve and as part of the Exeter Green Circle walking route" and "No public rights of way exist over this path and the owners have no intention to  dedicate any rights of way of any kind." The notices are signed by Trustees of Duryard Estate and Exeter City Council.