May I suggest that you narrow the birth date down a bit.
Do you know how many children she had? If so she probably would be about 18 at the first birth. If you know the youngest, the she probably will be between 40 and 50 at the last birth. This becomes more accurate as you know more children.
Do you know the age of her husband? she probably will be from about 5 years older to about 10 years younger than her husband.
What about the marriage date? Again she would probably be about 18 at the first marriage.
If she was 42 in 1933, she probably can be found in the 1900, 1910, 1920 and 1930 census which will give her age. Add one to the census date ie 1901, if she lived in the UK.
While it is not indexed with a little creativity you can find it in the 1940 US census.
Finally some city directories will give an approximate age. There are many directories that cover that period.