lucy24 - 6:09 pm on Dec 10, 2012 (gmt 0)
I thought that the rewriterule above was supposed to capture any url ending in some-old-url
Ah ha! You've got a beginning anchor. If you want to look only at the end of the URL, regardless of what comes before it, you have to leave off the anchor.
And don't bother about ^(.*/) because g1 will tear your head off and it isn't worth it :) Luckily there are approximately ten thousand earlier posts in this forum showing the correct way to capture the beginning of an URL if you need to save the part before your target text. Here maybe you don't, so just omitting the anchor is enough.