With the price of insurance these days, here's something I am seriously considering doing:
1. Buy insurance on your car as you would normally, get cheapest quote & whatnot.
2. Go find the absolute cheapest piece of rubbish car (I would pick a 1987 Citroen 2CV), find a numberplate of one online and buy yourself insurance for it for doing no miles + put your mum, your wife and everybody else onto the policy. This will typically come out at the price of a pack of crisps (perhaps a slight exaggeration, but you get the drift).
NOTE: this is perfectly legal. There is nothing stopping you from buying insurance on any car of your choice as you might be considering buying it/might want to drive it/whatever.
3. Keep refreshing your 2CV insurance. You might even get a decent discount on your main policy with a multicar offer! Buy yourself a second one just in case too.
4. If you happen to lose your no claims on your main policy or ever decide to buy a second car or anything of the sort, you have a back up set of no claims discount that you can easily use as and when.
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I think I'm gonna go down this route as I am pretty sure this will save me a load of money overall.