Mark 2.
Mark 1 overheated so I will use some aluminium tubing as a heat sink.

The Halcyon Scout Torch is only 190 lumens and is a bit dull nowadays.
Here is a very simple and cheap modification including batteries and charger for $45. (Cheaper if you have some scraps around)

1 x 1200mm length of 25mm PVC Tube (Bunnings $5.00)
1 x 2m length of 25mm Aluminium tube (Bias Boating $17.95)
1 x 210 O ring (1" OD, 7/8" ID, 1/8" W) (Bearing shop $0.22)
1 x Ultrafire Cree XM-L2 U2 1A 1400 Lumen drop in module (Kaidomain US$8.71)
1 x Battery deal (Deal Extreme) $US7.31 2 batteries.
1 x Battery Charger (Deal Extreme) US$6.20

pair of needle nose pliers
pair of sturdy wire cutters
hack saw.
1.6mm Allen key (small)
Small round file or bench grinder.
Hot glue gun or some other glue.

Remove the torch cap
Remove the current LED assembly.
Remove the 2 small Allen screws holding the Insulation Block to the reflector.
Remove the heat Sink and LED from the insulator block
Remove the Battery spring and  connection wire assembly

You should have all these parts

We won't be using the LED, 2 x screws and reflector, but we will use the insulator block and heat sink
Place the heat sink over a Ultrafire Cree XM-L2 U2 1A 1400 Lumen drop in module.
Put the O ring onto the drop In LED module to hold the heat sink in place against the drop in LED reflector. The O ring also acts as a insulator and keeps the LED module centred.

Put the new led assembly aside.
Grind or file a notch from the insulator block raised edge.

Insulate and loop the end the battery spring connection wire back on itself 12mm from the end and cut it off to resemble the original wire.

Manipulate the spring with pliers to make the overall diameter about 18mm.

Cut a 100mm length of 25mm aluminium pipe
Cut a 75mm length of PVC conduit
Cut a slot 12mm slot along the length of the PVC tube

Final look at all the parts

Insert the PVC tube inside the aluminium tube, this will need a little force, and push it until 5mm is protruding from the end.
Insert the spring with the insulated wire on the outside of the aluminium tube and the spring section inside the PVC tube.
Glue the insulator block to the spring end of the tubes so the notch fits around the spring wire.

Insert the assembly into the torch body. If the insulation on the wire is to thick, it will be a very tight fit, either use smaller insulation or grind a flat section along the edge of the aluminium tube. I also used a some O ring grease to slip the assembly into the body.
Make sure the wire loop fits into one of the 4 holes in the torch body.
Place a 18650 battery in the torch and screw the new led assembly and original cap onto the torch.