Mystery Area Title - 9b. S.C.

UPDATE: I received a couple of replies to this blog. One said that Worcester Park was in the borough of Epsom & Ewell. However, another email said Worcester Park is split between the extreme north west of the London Borough of Sutton in Greater London (east of the railway line that runs through the area) and part of the Borough of Epsom and Ewell in Surrey (west of the railway). So, it's possible the below could be correct.

A peculiar-looking area title has been noted over the years. It looks suspiciously like a Civil Defence area title but has the rather esoteric "9b. S.C." on it (see below). A few collectors have come across it but there is no definitive answer to the origin.

One recently sold on eBay (amongst a collection of other mainly CD items). I asked on Facebook about this insignia and someone was kind enough to point out that the seller was also selling some paperwork belonging to a warden from Worcester Park. Worcester park is at the very north of the county of Surrey. It would appear from this map on the IWM that Worcester Park was inside the borough of Sutton & Cheam (S.C.?).

Borough of Sutton & Cheam (IWM)

Lastly, Sutton & Cheam are part of Group 9 of the organisation of Civil Defence in London. Additionally, it is part of the sub-group of Group 9.

Details of Group 9 sub group

Lots of supposition but possibly an answer (or complete billhooks). However, why on earth did they go for such an esoteric name in the first place?

​Thanks to Nicholas Mayweather for the steer.