I'm originally from the east Midlands and spent a lot of time in the west midlands as I had a boyfriend who lived there, and I never heard 'mom' uttered, not once. Mind you I left the UK in the early 1970's. I was very surprised to hear 'mom' now used in the UK.
I read other things have changed in the UK, such as Halloween trick or treating. That is also copied from Americans. There used to be All Hallows Eve parties that involved apple bobbing and such, maybe a witch burning, but no trick or treating.
While I'm on a roll; prom dresses! I read on mums net people are buying prom dresses. What is all this about? Do you have Prom night there now, and High School graduations? How about homecoming dances, prep rallies, and homecoming footballs game, do you have them there now? Please tell me you don't.
I do see you have Black Friday sales/shopping now. In the U.S. Black Friday is the day after Thanksgiving, which marks the start of Christmas shopping. Do you have Thanksgiving Dinner there now? It's got something to do with Pilgrims you know.
Now I'm really warming up.
Are there still Harvest Festivals, and how about Maypole dancing on every English common? I hope they haven't done away with the stocks on the village green, or the ducking stools. If that happens, England will be overrun with wrong 'uns pinching rabbits or even bloomers off washing lines, and the old scolds and witches will go unpunished.
I think the last couple of generations have blurred American and British culture together. It's almost as if they don't know the difference between the two anymore. It makes me sad really. And it all started with the word 'mom'.