Janet, according to your previous thread, your mother was born in January 1925, Therefore at the time of the 1939 register she would have been 6 months past her 14th birthday. At that time education was compulsory up to 14, so it is likely that, wherever she had been before, by the time of the 1939 register she will have been in some kind of employment. Have you eliminated the only Margaret Machin in the register born in 1925? She was living in Scarborough with a family called Moss.
Dave