a friend once told me that if you remove the back panel from your marshall amp you will find that it is signed by the workers and the workers are all women is that true? I have A MG 100 series.

Only for custom shop, hand built and wired models. The MG is a mass-produced, lower budget version of a Marshall made on an assembly line by machines. You will not likely find it hand signed.

As far as it being all women, that is not true. Marshall is an Equal Oportunity Employer.