Finally have access to this on Ancestry. What a great source of information. Have noticed that quite a few birth dates do not match the ones I already had. So have decided these are more reliable than the ones I had. Any opinions on this.? Also, have noticed that someone has marked marriages for some of the children, and these have so far proved correct. Any idea as to who might have done so or why. Will have a good time searching for more details White
While I had used the 1939 Register through FindmyPast, I hadn't stumbled across the fact that it was also on Ancestry (probably due to the fact that Ancestry does not seem to be highlighting it like FindmyPast does).
However, I can answer your question from some research I did last year. The inclusion of marriages for women and other extra notations is due to the way the 1939 Register was used after World War II was over. From the National Archives site:
The Register was continually updated while National Registration was in force, when it was a legal requirement to notify the registration authorities of any change of name or address. This ended in 1952, but since 1948 the Register had also been used by the National Health Service, who continued updating the records until 1991, when paper-based record keeping was discontinued.
Changes of name for any reason were recorded; in practice this was mostly when women changed their surnames on marriage or re-marriage, but also includes changes of name for any other reason, such as by deed poll.
The majority of these name changes appear in the indexes so you can search for a person using either their name in 1939 or any subsequent name.
The listing of married names can be very useful in figuring out who a given woman may have married, especially for those more common names (first name and surname), as it will indicate the correct marriage to look for. The marriage notation will often even include the exact registration details.
As to the accuracy of birth dates, that is a little harder to quantify. My usage of the 1939 Register to date has been primarily in relation to Irish born people who crossed the Irish Sea to live and work in England. While in some cases the birth dates match sources from Ireland, often they do not match. However, in my research I have found that the Irish - particularly from County Clare where my recent research has been focused - are remarkably casual about dates of birth etc. The dates in Civil registrations are often days, weeks or even months after the child is baptised in the Catholic Church so as to avoid paying a fine for late registration when the civil registration is well after the baptism. Even if the civil registration was only a couple of weeks after the birth, the "birth date" is still often after the baptism date. The rule of thumb for the Irish tends to be to treat the Catholic baptism as a good proxy for the birth date, since it normally happened no more than a couple of days at most after the birth and often on the same day.
For those of English, Scottish or Welsh descent, I have less to go on. And there could be several factors to consider. For a start, if you are dealing with a very common first name & surname combination, there is always the possibility of having the wrong person - unless you have sighted the actual certificates or registers and even then the possibility of error exists.
The other equally likely scenario is that like many of the Irish, the person may just be using the date they "think" they were born on. The stringent personal identification requirements of the the late 20th century had yet to take strong hold, and unless you were travelling outside your home country a given person might not have any documents stating their birth date.
All you can really do is record the dates you find with the relevant sources noted.
For the Irish mentioned above, I have been using their birthdates from the civil registration if that date occurs before the Catholic baptism date, If the baptism date is the earlier, then I use that data as a "circa" date, and record the civil registered birthdate as an alternate with a note explaining why the baptism date is the preferred proxy. If other records indicate another preferred date in adulthood that is also noted accordingly. However with the Irish (particularly those that emigrated to the USA), while recorded birth dates often don't match those from their actual birth registrations and baptisms, for those born prior to WWI, they also rarely use a single birth date in subsequent records, as although the day and month might be stable, the year of birth often moves by up to a decade.