Where does the phrase, "Keeping Mum" come from? When you have to keep something quiet.

"mum" meaning silent (hence "keeping mum") is an old word going back at least several hundred years which actually means to be silent, and it is derived from the still older medieaval English "momme" also meaning silent. Obviously it is related to our present day verb "to mumble" - still in common and frequent use.

It is completely unrelated to the word "mum", short for "mummy", meaning mother.

Would that be related to the "mummers" who would travel round with plays? I wonder whether they mimed some of it?

There may be a connection, but the immediate origin of "mummers" is the French "momeur" meaning "mask wearer" (in turn from momer - to wear a mask)

Still do Susie. My Morris side does a mumming play - see http://www.adlingtonmorrismen.ik.com/p_Dmummers.ikml We are one of many around the country.

I don't think so. It's certainly all spoken now (bawled rather). Mad Tom's derivation is plausible, but I've also heard it's from the German "mummer" meaning "disguised person". Incidentally, mummers were also often referred to as "guisers" (short for disguisers), giving rise to the modern "geezer".

Fascinating. Thankyou folks.

Anyone got any other sayings they don't know the origin of?

I like this website
http://www.phrases.org.uk

You learn all sorts of things.