If you don't have one I'd recommend getting one. I have a clear plastic box with clips on it, nothing fancy.
Plasters
Anti septic
Hand san
Fruit pouches - long date
Biscuits - long date/ digestives
Scissors
Silver crinkly blanket
Rain poncho
Safety pins
Bandage
De Icer spray
Tissues
Plastic bags - handy any time of year for unexpected mess
Lighter
I will also have a 2ltr water and a blanket/old coat.
I have a solar radio with phone charger but I don't keep that in the boot. I bought that in Feb after we lost power and phone signal at my house for 5 days. It was nice to hear the news at least!
It might seem a bit much but it really takes up very little space and when I hear of people stuck on motorways for hours or at the side of the road in a break down I think I'd be happy to have it.