The "Dorcy" brand products include LED bulbs to replace ordinary bulbs.
They come in various ratings for 2x D, 3x D, and 6V Lantern type torches.
Also suitable for AA, & C type battery torches.
Claimed 10 Year life or 100,000hrs. as well as low power requirement.
Dorcy also make waterproof torches for divers, have done for years.