Thanks for everyone's advice, but I think we're all going a bit overboard now
I've already thought about using the power cable as a pull-through, but have decided against it.
I did have many other cables through this pipe at one point; Component video cables, Stereo Audio Phonos, etc. When I removed these, I tried using them, unsuccessfully, as pull-throughs so I'm not going to risk pulling-out my power cable and not being able to get it back.
I believe the pipe is 2" diameter but, as the hole will be hidden behind the TV anyway, I think I might just drill another.
I'm also considering drilling a hole in the pipe before the right-angle, feeding the cable through that (i have rods) and then back into the pipe at the other end before the second (more obtuse) bend.
I'm going to post some pics of my set up, if you're interested; this was all done before I found "AVFORUMS" and I'd do so much of it a lot different having seen some of the excellent work on here.
Thanks again for all of your input.