TSEM6075 | Legal background to trusts and estates: legacy to a minor beneficiary
From HM Revenue & Customs · Trusts, Settlements and Estates Manual
A minor beneficiary is unable to give a valid receipt. A legacy to a minor results in a trust for that minor. This may be a bare or simple trust. The personal representatives pass the legacy to trustees, who are able to give the valid receipt, to hold in trust for the minor.
There are further details at TSEM6321.