Seems like a suitable place to share this project:
This type of xenon tube strobe is obsolete and can be found very cheap. I happens to have a few with burnt light bulb.
Waterproof Emergency Xenon Strobe Light Portable uses 1 C-cell | eBay
Measured it with a home-made lux meter, it gives 40 lux at 0.5m, with some calculation this should be about 125 lumens.
DIY LED conversion:
Take out the circuit board and light bulb, replace with a very simple 555 timer circuit in astable mode, with the resistor-capacitor combination I used in the circuit diagram it gives about 3.5ms duty cycle at 1.5 Hz.
Battery was C battery in the original strobe, this need to be changed into 26500 lithium battery.
For the actual strobe part, I used six 3W green LED in parallel (not CREE, just the cheap ones), the LEDs are rated for 700mA, with no resistors they are actually over-current to 2A. The duty cycle is so short they don't actually heat up at all so it should be fine, even if burnt they are dirt cheap to replace.
Total cost: I made 3 of this for less than £40.
The result is really bright by eyes, but hard to be captured by video. Measured 300 lux at 0.5m, so about 1000 lumen, bear in mind that strobe is all-directional.