I couldn’t get the loop edge select cut thing to give me a parallel ramp, tried several times just kept doing this:
Can anyone suggest what I’m doing wrong?
I’m not SURE what’s going on, but I think it has something to do with when you’re using the loop cut, you may need to select ‘Even’ - also you might need to first loop cut through the very centre of the pyramid to create that initial straight line?
Perhaps someone can let me know if I am warm…
No, I’m really not sure what’s happening myself, I’d like a clearer explanation too. 
@Dylan_Froment Did you put the first cut in the middle at 0? Did you put the second cut right up against the first cut at 0? If you did you should be able to shift them around and they should stay straight. I’d suggest reviewing lecture 28 from the 5 minute mark and see if you can figure out what went wrong.
(Edit)
I was able to recreate this by placing 2 loop cuts at once (using middle mouse wheel) instead of placing one at a time. So to get this straight, you need to place one cut. Click. Then place a second one and move it right up against the first. Don’t place more than one cut at a time. (Don’t use the middle mouse wheel.)