Be Mother Meaning

(idiomatic, Britain) To pour out tea for others.

Example:   Ah, here are the cakes and tea; shall I be mother?
2009, Kate Atkinson, When Will There Be Good News?, page 277
  They went to a cafe and had afternoon tea.
'Shall l be mother?' Marcus said, lifting a utilitarian brown teapot, all cosied up in something that looked like a bobble hat.
2012, Betty Neels, The Final Touch
  'Be mother, will you, Charity? Teile and Letizia have a watered-down version.'
So they had a pleasant tea, although Charity kept an anxious eye on the clock, keen not to outstay her welcome.