Wills Act 2008

If there is a disposition to a person in a will that is expressed to fail if there is either – a want or a failure of issue of that person either in his or her lifetime or at his or her death; or an indefinite failure of issue of that person – those words must be construed to mean a want or failure of issue in the person's lifetime or at the person's death and not an indefinite failure of his or her issue.

This section does not apply if a contrary intention appears in the will except where the result would be to cause a failure of the disposition.