Earlier this week, I was padding around a well known supermarket when I had a thought: “It’s winter. I’ll probably need screenwash.”

But with a head full of shopping list, I ended up chucking the regular haul of groceries in the trolley. Naturally, Murphy’s Law struck the next morning as the low washer fluid lit up on my Volvo V40.

Recalling that the supermarket was punting sensibly priced screenwash for about £3.50 for three or four litres of ready-to-use juice, I went back. Naturally, the shelves were bare, save for half a dozen one-litre bottles of ready mixed – for four quid a pop.

I understand the rules of supply versus demand as much as the next person, but £4 for a litre of own-brand is out of order.

That’s almost three times the price of a litre of diesel. And like diesel, it’s a distress purchase; you need it when you run out. With temperatures dipping to -10deg C, it's not like you can do without it.

And I don’t know how big the average washer bottle is, but it’s got to be a couple of litres. So I suspect, faced with spending £8 to fill a bottle, cash-strapped motorists might not bother. And that's extremely dangerous.