Do prepaid SIM cards still exist in London and which Telco is best to purchase from?

I'm from out of town and going to London for a couple of days before moving on to the rest of Europe. Staying in the Kensington area. I use an iPhone but I was thinking of using an old Nokia and purchasing a prepaid SIM card while there. If that's possible. Do they have those over there? Just for temporary usage? Also which telco would be the best to purchase that from and whereabouts?

Prepaid phones are very common. Go to a phone shop and they will give you a good deal.

It might even be cheaper to buy the whole phone than using your old one with a SIM card. You can pick up a pay as you go phone up for around £10.

My local Tesco supermarket sells Pay As You Go (PAYG) SIM cards from all major mobile companies for £0.99, and you can charge the SIM at the sales desk from as little as £5. Ask the sales assistant for the best current deal as they frequently change. All independent phone shops will offer a similar service (Carphone Warehouse, Phones4U, etc).
It would help if you had some idea of how many texts and calls you're likely to make, both national and international, and if you require data services.

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