All of which (except the cheque, which we can ignore - nobody in the UK has a chequebook any more) depend on the same communication infrastructure that the app does.

I imagine that if all banking apps go down as a result of war then bank websites, credit cards, basically any other digital financial thing will also be down.

A lot of banks in the UK have mobile-app-exclusive features / services. I imagine this is because of security, but it also makes little sense. If you don't have a smartphone it is about 5x harder to do anything online-banking related here. I remember when I went camping a bit ago my phone died and I was unable to unfreeze my card.

Also, cool username =)

Do people write cheques in the UK?