OK - here's the pictures of my bodged tesco 3W Cree lights, as advertised
here. In the Luton store they cost £10 each.
You can unscrew the very top to look at the LED, a section futher down, and also the base to insert the batteries, which also houses the switch in the end.
What I did was to saw through the barrel, at the end of the thinnest bit, leaving the rest to be thrown away:-
It's very thick aluminium, so it took about 5 minutes with a little hacksaw.
I then took the screw capped end and held it against the bulb stub, and simply taped it together with electrical tape (very high tech). I drilled through the switch to make a hole to put the wires through, and soldered them onto the battery contacts.
The top was then screwed back on, and I found I had a U shaped plastic holder which was bolted onto an old Cateye handlebar mount, and the torch fitted neatly into that. I converted the second torch the same way, and wired them into a simple switch.
It's wired to a block of 12 x AA rechargeables in my seat pack which gives 6 hours of mega bright light.
This was all done in a rush on Friday afternoon for the FNRttC, so I could have done it a lot neater if I'd taken my time. However, someone asked if they were a £200 set of lights, to which I was proud to confirm they were in fact £20.
Edit - the Smart 1W below the handlebars is angled to show up the road immediately in front of me, whilst I have the Tesco lights pointing further up.