"Dead, and never called me mother!"

Sadly, I don't think you'll get a very satisfactory definition of what that line meant in that sketch. It is Monty Python - who often said virtually meaningless things.

Having said that, we can assume The Big Cheese was effectively 'Mother' to poor Flopsy, who certainly never acknowledged that relationship verbally. Much to his annoyance, perhaps; he might have felt the rabbit should have been more effusively grateful for the doting treatment it received prior to its sudden untimely demise.

Doubtless there have been plays and films where the line will have been delivered in earnest (bewailing dead infant too young to have ever talked, or adopted child who never discovered his parentage before dying dramatically on set). It was may well have been something of a 'catchphrase' among the Pythons, evocative of absurdly overacted pathos.

It made me laugh to watch it again, anyway. But I'm English, with a warped sense of humour. I don't think many Americans of today would like it one bit.

The phrase means that Flopsy never had a chance to call the Big Cheese mother, or will never know the Big Cheese was her mother. This is obviously nonsensical - an important element of Python humor.

It does seem to be an East Lynne reference, referring to a scene where a child dies without ever knowing who his true mother was, although she went to great effort to be his governess and care for him.

Although the line did not actually appear in the novel of East Lynne, it probably occurred in a stage adaptation according to this BBC radio writeup:

I would love to know who coined “Dead, dead, and never called me Mother!” one of the best loved theatrical misquotations of all time. I have before me my grandmother’s acting script, from the 1880’s or 90’s... Madam Vine (the disguised Isabel) cries, “Oh, he is dead! – he is dead! Oh, William! Wake and call me mother once again!” In her next speech, to the faithful maid, she cries, “See here! – my child is dead! And never knew I was his mother. I don’t care what I’ve been, I am his mother still."
...There were 17 different published versions of the play ( not including all the pirated ones) and it would seem that the line ‘Dead, dead and never called me mother’ appeared in one of those.

Wikipedia is a little vague on the details of the East Lynne plot, but in at least one film version the heroine leaves her husband when her son is still a baby, to return years later, disfigured and working as a governess for her son. The son later dies in her arms - at which time she presumably utters this line, heartbroken that her son died without ever knowing she was his mother (at which she promptly dies herself).

In the sketch it doesn't seem to have any particular meaning other than fitting with the overwrought tone of the scene (mocking many films made in such a style), and with the generally absurd style of humour for which the Monty Python team are renowned.

I have been interested in this quote for some time. I remember it from a series called "The Monocled Mutineer", which was shown by the BBC about 15 years ago, based loosely on the life of Percy Toplis.

In one scene, an officer makes a very over dramatic exit, and when he has gone, a fellow officer uses this quotation.

My knowledge is that this quote was used by music hall artists that wanted to criticize someone who had over dramatized quite unnecessarily.