aria-describedby flattening things

Most of the content on this page has aria-hidden="true" for easier screen reader testing

Help text: just text

If the address entered is different to the one in your organisation settings, your organisation address will be updated.

When it gets focus, the field sounds something like:

Find your address, search text field.
If the address entered is different to the one in your organisation settings, your organisation address will be updated.

Help text: text with a link

If the address entered is different to the one in your organisation settings, your organisation address will be updated.

When it gets focus, the field sounds something like:

Find your address, search text field.
If the address entered is different to the one in your organisation settings, your organisation address will be updated.

Help text: text with structured content

When it gets focus, the field sounds something like:

Find your address, search text field.
If the address entered is different to the one in your organisation settings: bullet your organisation address will be updated; bullet something else too.

Note how the list loses it semantics. Usually it would sound like "list, two items" and allows users to move one item at a time. Here the whole list is presented as one long bit of text.