I’ve been reading this in Wikipedia:
Mothering Sunday is not actually a ‘be nice to your mum day’. Traditionally, families made a special effort to get together on the fourth Sunday in Lent and they all went to their local church (Mother church) for Mass. Later, live-in servants would be given the day off: girls used to bake their mothers a Simnel cake, and, it being Laetare Sunday, the family would relax from Lenten austerities a little, which is why a cake would be wanted. If your church has them, you may see the priest in pink vestments on this day, again to rejoice that Lent is halfway over.
I think, maybe from next year, I will reintroduce the simnel cake in our house.