Lightbulb moment

My mother-in-law is worried that there may be power cuts this winter, so we bought some batteries for various torches and light devices she has. This one has a nice new battery but it's dead. We've checked the contacts and there is no corrosion, but it doesn't want to light up. It's an old fashioned incandescent lamp that uses a wire filament to generate heat and a little light. You can get LED replacements which will generate more light and a lot less heat, but I don't actually want a dozen...

I took this picture to identify the lamp, which turns out to be a common screw thread size, and is widely used, but getting just one of them is more of a faff!

Back blip.