SID stands for Speed Indicator Device. These are the signs which flash if you are driving in excess of the speed limit.
In 2011 Wiltshire Council allocated one to each Area Board, with criteria for where they could be used.
Towards the end of 2014 WC told parish councils that funding was being withdrawn and that parish councils would have to take over the costs of the scheme if they wanted it to continue.
As parish and town councils (including Hilperton) decided NOT to take on the funding of theses devices the SIDs will now be withdrawn and, presumably, sold to another local authority.