A town centre street in Buckingham has a circular 'no right turn' sign with a rectangular sign (white background with black lettering) below it bearing the message "For lorries longer than 20' (6.1m)".
Please could you advise me if this complies with the 1994 regulations. If it does not I will get on to the county council straight away as I know that they are shortly to order a new batch of road signs.
The main lorry length restriction sign is a circular sign which may be in Imperial only, or on separate Imperial and metric circular signs (as for road widths).
This, however, is a supplementary written information sign which I cannot see is covered by the Regulations.
By analogy, you could argue that it is generally confusing to have two sets of measurements on the same sign, a principle one finds throughout the Traffic Regulations and General Directions with the single exception of a limited number of bridge height signs.
Your approach might be as follows: "I cannot see that these signs are permitted or authorised under the 1994 Regulations, therefore they must be _ultra vires_ i.e. illegal. If they are not permitted, the sign must be removed, or replaced with two separate signs, one in Imperial, and one in metric".