Otherwise:-
https://www.legislation.gov.uk/ukpga/19 ... ection/192“road”
(a)in relation to England and Wales, means any highway and any other road to which the public has access, and includes bridges over which a road passes, ....
Looking at streetview, there are various traffic signs which appear to be there to inform road users of what is either a traffic regulation order (TRO) or something similar under any Humber Bridge Act or whatever. Now, with any TRO, there are typically loads of exceptions including something on the lines of "... on the directions of a constable." (Nowadays extended to include PCSO, Traffic Officer and I suspect on the Humber Bridge, something like "employee of the Humber Bridge Authority.") The point being that there will be times when eg traffic has to be directed the wrong way down a one-way street. The police also have a general duty at common law to direct traffic.
A problem can arise if different officials take uncoordinated action or what they say is misinterpreted.
Somebody - possibly Ben Lovejoy - posted about a Critical Mass event where some police were directing riders to ignore traffic lights to keep them moving and others were stopping and reporting them for doing so.