Canal & River Trust has confirmed in a notice dated 11 February 2021 that wide beamed boats may only use parts of the north Oxford canal if they are booked to do so.
"The north Oxford Canal between Braunston Junction and Hillmorton Locks is a narrow canal, not suitable for wide-beam craft.
Access to the marinas on the north Oxford is permitted but only at pre-agreed times and must be done in a single journey (i.e. not stopping between the marina and the destination)."
C&RT's full statement and details of how to book a passage are here.