1939 census linked query.

[Linna]

On looking for relatives on the 1939 census I came across an entry that made me wonder whether it was only marriages that occurred after 1939 that were recorded on the 1939 registration form. 
My reason for asking is that I have found an entry on the 1939 census that shows that one of my ancestors later changed her name from Rose Merrifield to Rose Shelley. (RG101/6923E/002/29 Letter Code: WKEY). My first thought was that Mr Merrifield had died and she remarried but her husband didn't die till 1974 and I can find no divorce or remarriage (internet searches only) for a Rose Merrifield to a Shelley. I have found her death in 1973 recorded under both Merrifield and Shelley so it seems she may have been cohabiting with Mr Shelley.
I can understand why, for appearances sake, a man and woman living together would want to share the same surname and might therefore register a change but did people need their identity card to obtain new ration books. If so, then  Is there anyone who knows about rationing in the 40s and 50s who can tell me what was likely to have happened.
I've come across articles about rationing and identity cards but none mention what identification, if any, a person needed to obtain a ration book.
I wonder if you are able to shed any light on this.
Thanks

[groom]

The name change could have come a lot later than the need for ration books, as the 1939 Register was in use up until 1991. Rationing ended on the 4th July 1954.

From The National Archives

The records of the 1939 Register were subsequently used by the National Health Service at its inception in 1948 and became the NHS Central Register, transferred to the Health and Social Care Information Centre (HSCIC) in 2007.

The records remained with the NHS up until 1991 – therefore some changes of names between 1939 and 1991 are listed in the records

[KGarrad]

Identity cards, and later ration books, were distributed by the local council.
And rationing ended in c.1955. (I was born in 1953, and had a ration book!).

The 1939 National Register (NB, Not a census!) shows changes in name.
Usually these changes are by marriage, but probably other name changes were accounted for, too.

Don't forget that, under the laws of England & Wales, a person can call themselves anything they like!
Just as long as there is no intention to deceive or defraud.

[ScouseBoy]

Shopkeepers such as Grocers  were responsible for collecting the coupons at first.   Government Inspectors would visit the shopkeepers to ensure that the paperwork was being done properly.

[Jebber]

I have a couple of instances where alternative names were added, neither changes were through later marriages. One was where the couple were known  by two totally different names, the other was simply a change of name.

Jebber

[ScouseBoy]

I believe that  Ration card holders  had to nominate  who their grocer  was to be.  And Butcher  was as well.

Inspectors  would visit the shops  to ensure that they were  following the correct ration procedures.

[robbo43]

On the basis of the National Register taked on 29 Sept 1939 everyone was issued with an identity card and a ration book (usually buff but green for pregnant women, nursing mothers and children under 5, and blue for children 5-16 as the rations were different for these groups -according to records but I have a pink one). You had to be registered with a supplier or suppliers who were the only people you could buy rationed food from, but you could have one supplier for meat, say, and a different one for groceries. Clothing, soap & fuel were also rationed. Changes in name for any reason would have to be notified.

[Linna]

Thanks everyone for your help. That's clarified things for me. Thanks again.