It has been brought to WALC’s attention that some Parish Councils have bought or intend to buy speed restriction signs indicating 20 mph to be sited within a 30 mph restricted area. If they are installed and they have a red border (as do official speed limit signs) it could have the effect of invalidating the official speed limit. Offending drivers would thereby escape punishment even if exceeding the 30 mph limit.
With that in mind, WALC would strongly advise Parish Councils not to take this action and to work with your highways authority to ensure that all signage is legally enforceable.
We have been sent this formal statement concerning this matter. Although this is from Warwickshire, the principle is likely to apply in the West Midlands as well.
"Warwickshire County Council (WCC) are unable to agree to Parish Council's purchasing and installing '20'mph signs/posters on the Highway. These signs are not within the Traffic Signs, Regulations & General Directions Manual. We only install signs on the Highway that are approved and listed within the TSRGD. Warwickshire Police adopt the standpoint that on routes where the speed limit is determined by a system of street lights (restricted roads), where repeater signs, roundels etc. are not permitted; should not have additional speed limit signing of any kind. On routes where the 30mph limit is supported by a Traffic Regulation Order, then no signs where the round border of the legend is red could be permitted as this would invalidate the Order. This could result in any driver caught speeding, being challenged and due to the '20'mph signs, the driver will not be able to be prosecuted. Technically, Black or Green bordered signs have been used in other area’s and whilst these technically don’t invalidate the order, Warwickshire Police would support advice that these are not installed upon the highway".