What's the Brexit angle?
The retail arm of a company expands its fulfilment workforce to handle its retail growth in the UK - this work is most sensibly handled somewhere on this island, whether or not this country remains a member of EU.
Meanwhile globally-relevant technical departments also recruit because they've got plenty of development work to do. Doesn't matter where on the planet this work is done, but the UK has plenty of relevant skills and a first world infrastructure - so is as good a place as any, and again EU status is irrelevant.
Whatever your view, this is neither in spite of nor because of Brexit.