I just noticed a post about a frozen headlight washer and he mentioned additive for the windscreen washer fluid. For those folks out there who don't normally get the ridiculously cold temperatures that are happening, I've got a tip for you . In this frozen wasteland of Western Canada we use a lot of Methyl Hydrate. (Meths) Put it in the fuel tank, it's already in the washer fluid and I never dilute it, and it works to unfreeze doors, windows and locks. "Gas line antifreeze" is usually sold in small , expensive bottles. I buy a gallon jug of Methyl Hydrate at the Hardware store for about a tenth of the cost per oz and put it in smaller containers. I have no clue if the UK uses Gas line antifreeze normally so if you do, Have a nice day, if not , I hope this may help. 