Cool carbine. I have No5 with a similar size barrel, all I can say is ouch! That puppy must have some kick to it.
This conversion must have been done after WWII because it has a Weedon stamp on the receiver and bolt. I'm sure it wasn't done then though. There's no wood to metal barrel contact at the front band so it must be fully free floating like a No5. I'd like to try it at the range to see how it does.
BTW its missing the nut for the rear sight screw. - Bill