Selling shares designated for a minor

I bought some shares for one of my children when they were aged under 18. These were certificated shares (ie there is a share certificate) in a U.K company.

These shares were purchased with a designation  ie the share certificates shows my name / address followed by the initials of the child (ie XZ).

My child is now over 18, and I now wanted to sell these shares for her. There is no CGT issue as the overall value of the shares is not sizeable.

I wanted to know whether it was mandatory for the shares to be re-registered in the child’s name now that they are over 18 prior to selling them, or whether I was legally entitled to dispose of them / sell then on her behalf (ie as the share certificates currently stand).

Thanks in advance to all who can assist.