Thanks all for your suggestions and assistance, just wanted to update that I managed to argue successfully that the advance warning was insufficient, and that it had been acknowledged as such in the notice of rejection.
The council was not represented, but they did submit an evidence pack.
Anyhow, relevant extract from the adjudicator's reasons:
The restriction sign relied upon by the Enforcement Authority is that prescribed by Diagram 619 at
Item 12 in Part 2 of Schedule 3 to the Traffic Signs Regulations and General Directions 2016, as
indicating 'Motor vehicles prohibited'.
In its Notice of Rejection, the Enforcement Authority states, "Please note that the signs are compliant
with the Traffic Signs Regulations and General Directions 2016 (TSRGD) and approved by
Department for Transport, however, we have taken on board the residents feedback regarding the
signs, and are implementing new signs at this location improving clarity on the restrictions."
The Enforcement Authority have submitted images of advance warning signs, although it is not clear
exactly where these all situated in relation to the alleged contravention. However, the sign presumably
before this location has the Diagram 619 symbol with an associated plate bearing the legend 'except
authorised vehicles'. However, although Paragraph 15(1)(d) does authorise "permit holder" or "permit
holders", and, where appropriate, a permit identifier, there is no authorisation for 'except authorised
vehicles'.
It does remain the responsibility of the motorist to check carefully at all times whilst driving their
vehicle, so as to ensure that they do so only as permitted. This includes making sure that they comply
with all restrictions and prohibitions indicated by the signs. However, it is also the responsibility of the
Enforcement Authority to ensure that restrictions and prohibitions are clearly signed. This means not
only that signs are compliant but also that by their size, position and number, signage in totality is
such as is adequate to inform the motorist of the requirements.
The Adjudicator is only able to decide an appeal by making findings of fact on the basis of the
evidence actually produced by the parties and applying relevant law.
Considering carefully all the evidence before me I am not satisfied that, on this particular occasion,
the restrictions was sufficiently clearly signed.
Accordingly, this appeal must be allowed