Dudley hand vac
You are half correct on both fronts, the Dustette was a hand cleaner manufactured by Hoover Limited, it looks nothing like this cleaner.
On the other hand you are correct that it was manufactured for sale by the CWS, and sold under the "Dudley" brand. There is a bit of a history around this company. The earliest knowledge of it would be around the mid to late 1920s when it produced a cleaner called the Eltra, this looked very distinctive having a relatively short body with an elongated, "stepped" chromium rear. This same model later appeared as a "Bustler" and later again as a Dudley (for CWS). Bustler are also known for their "stick" vacuum cleaner from which I believe this was developed, although they crop up from time to time, I have only ever seen them as "Bustler". Unfortunately I cannot give you exact dates, but it appears that Bustler are pre WW2 and Dudley (CWS) post WW2 - Dudleys seem to go on until the early 1960s.
The styling of this cleaner would indicate that it is pre-war although it is possible that production continued for a period after WW2. It is of course missing its bag which is attached on the other side of the cleaner from your picture - the bag was navy blue.
Yes, I have one of these cleaners, and will post some pictures when I have a chance, probably next week
Al