Lights

I ordered one of these, because for £2.87 with free UK delivery how could I resist ?

G3 CREE Q5 400 LUMEN FLASHLIGHT/TORCH: Amazon.co.uk: Sports & Outdoors

It took weeks to come. It is very bright at first, but quickly runs the single AA battery down.

Had a quick rummage with a volt meter: It seems that there are no driver electronics in it, it just applies the battery directly across the emitter and lets nature take its course. The emitter draws about 300mA at 700mV, and is fairly bright. I didn't measure its current draw at 1.2V, but I estimate it at roughly "too much".

So I've ordered 6 more, and I'll connect up all 7 in series and use a transistor to drive them at constant current from a bank of 6 AA NiMH batteries.

The circuit you're proposing won't deliver the constant current required by non-linear devices such as LEDs.