Woollen suit with f.m label

I have found this woollen suit which needs a bit of tlc and cleaning. It has the label f.m which I I have seen before on another dealers suit. Can anyone shed some light on this?

 

A guess, but Fortnum and Mason?
This thread mentions that Cojana, a quality coatmaker, supplied Fortnum and Masons and this is in line with their quality and styles.
http://forums.vintagefashionguild.org/threads/cojana-london-harrods.35698/page-2#post-449537
Many department stores had garments made for them by established companies which would then only contain the department store label.

 

Thank you Melanie, I have emailed Fortnum and Mason in hope that someone in their archives has information too.
Would you say it's 50's?

 

Always go with first instinct ;) thank you Mary Jane

 

It is more likely to have it at the front, otherwise the zip would fall at the front. It has been altered but not finished, so doesn't sit on the mannequin well

 

I did think 60's too.