By enlarge the tow paths are private land, although there are some lengths of towpaths that are rights of way (footpaths).
The owners (BW / C&RT) have granted access to the 'other towpaths' under what is called 'a permissive footpath' which basically means that the land owner has given permission for you to walk on their land.
Permissive footpaths can be closed, or the permission revoked, if the landowner wishes - a typical example of this on 'shoot-days' when the permission is revoked for 'the day'.
Unfortunately C&RT are not in a postion to be able to 'close' their permissive footpaths due to the agreement the 'signed up to' when they were handed the poisoned chalice AKA 'the canal network;.
From the transfer documents :
2 OBJECTS
The objects of this Settlement (the “Objects”) are as contained in this Clause 2.
2.1 Subject to Clause 2.2 and 2.3, to hold in trust and retain in perpetuity for public benefit the Infrastructure Property for the following purposes:
2.1.1 to operate and manage the Infrastructure Property for public benefit, use and enjoyment including:
(a) for navigation;
(b) for walking on towpaths; and
(c) for recreation or other leisure-time pursuits of the public in the interest of their health and social welfare;
2.1.2 to protect and conserve, for public benefit, sites, objects and buildings of archaeological, architectural, engineering or historic interest on, in the vicinity of, or otherwise associated with the Infrastructure Property;
2.1.3 to further, for public benefit, the conservation, protection and improvement of the natural environment and landscape of the Infrastructure Property.
2.4 The Trustee must obtain the Settlor’s prior written consent before:
2.4.1 disposing of any part of the Infrastructure Property
a) by way of freehold; or
b) by way of any leasehold disposal that would have the effect of restricting any generally available public access to the Infrastructure Property existing at the time of the disposal (for the avoidance of doubt the Parties agree that all towpaths are generally available to public access at the time of disposal);
2.4.2 seeking to amend this Settlement in any way (and any such amendment shall be ineffective without the Settlor’s prior written consent);
2.4.3 restricting pedestrian access to any part of the towpaths within the Infrastructure Property; for example by charging a fee for access, save that consent will not be needed for any temporary restrictions either to allow maintenance/repair works or to protect persons from risks to their safety;
2.4.4 diverting the route of any towpath or part of a towpath, other than as permitted at Clause 3.5.1