 The law also allowed for the hanging of children aged seven years or more . Mary <unk> , " but sixteen years of age " , was burned at Winchester in 1738 for poisoning her mistress . An unidentified 14 @-@ year @-@ old girl imprisoned at Newgate was more fortunate . Found guilty in 1777 of being an accomplice to treason , for concealing whitewashed <unk> on her person ( at her master 's request ) , she had been sentenced to burn . She was saved by the intervention of Thomas <unk> , 1st Marquess of Bath , who happened to be passing . 
