Yes, I cannot get hold of the Birth Cert online, it will have to be a posted one and as I live in Denmark it will take several weeks. However on the national bmd I can see that the mothers name is also Shepherd making it an illegitimate birth.
That would make her a spinster at the time of marriage however I am aware that Herbert was married previously and there were no children from either marriage.
I have been advised that the copy of the will I have ordered will take some time due to a huge backlog and I am really at a loss on how to find out more information.
I have found a marriage for a Silvia Shepherd to a Reginald Lund in 1933 in Yorkshire which could possibly be her mother but cannot find them on 1939 census.