[DaveJ|UK]

I think you misunderstood what I meant. Perhaps I can explain better.

I'm not talking about the redirect to the new url format.

I know you have a function to generate the url's.

Before you display the content, you should check that the url requested is the same as the one you expected.

If the request is for:

/the-wrong-url-101.aspx

But your function tells you it should be:

/the-correct-url-101.aspx

then you should redirect to the correct one. If not, then display the page as normal.