I don't know where you got this from, but it is not true.
This page on the IND website contains the following
Transferring your existing immigration status into a new passport.
If you want to transfer limited leave to enter or to remain in the UK to a new passport, you will need to use Form TOC. Limited leave means that you have permission to stay in the UK only until the date stated in your visa or stamp in your passport. You have to apply before the end of that limited leave.
If you want to transfer indefinite leave to enter or to remain the UK into a new passport, you will need to use Form NTL. You can apply for indefinite leave to be transferred at any time that you have such leave.
And
this page makes it clear that the fee for a postal application is £160, and that for a "premium" application is £500.
Elsewhere on the IND site it is made clear that there is no need to do it, though - you can simply carry the old passport with you, or the letter on which leave was granted. (Since the site was relaunched, I can't immediately find a link to that para...)