gas

One of the minor annoyances I haven't mentioned before is that the letting agent switched us to a new gas company, who sent us a new meter key with a letter saying "This is so you don't have to deal with bad debts from former tenants." So I was not much amused to discover that the new key already had a debt of £73 on it. We phoned them, and they cancelled the debt, but it'll take a week to go through (because their computers are actually powered by gnomes or something). Until then, we get 10p of gas for every pound we put on the meter, because 90p goes towards the debt, and 10p of gas is not quite enough to run a bath. This wouldn't be as much of a problem if we had more spare cash at present, and if the weather wasn't starting to get cold.

gas/electric keys

(in answer to resonant 's question)

Some people in the UK get bills from their power company and pay in arrears. But people with bad credit, and tenants generally, aren't trusted to owe the power company money, so they have to pre-pay. In the old days the meter had a coin slot, and you'd put a shilling in and the power would come on for some number of hours. But the power company got fed up of sending people around to collect the money, so they came up with the key scheme. You have a physical object called the "key". When you want to prepay for something, you go to a newsagent's or similar, hand them some money and say e.g. "Please put £5 on this key". (The newsagent gets paid by the power company to do this; they don't take a cut of the amount directly.) Then you go back home and put the key in the meter, and the meter says "There is £5 on this key" and increases your prepayment balance by that amount.

For no reason I can discover, although our electricity and gas are supplied by the same company, the electricity key is a long folding strip of plastic containing an integrated circuit, but the gas key is an ISO/IEC 7810 card.

Prepaying for your gas and electricity in this way tends to be a lot more expensive than getting bills, but it's not easy to switch away from it.

Edit: Oh, this was behind the joke in "A Tall Story" :

Just as she’d finished knitting, the light in their room went out with a quiet click, and so did the lamp at the top of the tower. [...] "Don’t worry," said the lighthouse-keeper, though he looked a bit worried too. "It’s probably just that I need to put some more money in the meter. We’ll have it right as rain again in no time at all."

because it would be ridiculous to charge a lighthouse for electricity in this way.