Sir Thomas de St. Omer was a Justice and Sheriff of Norfolk and Suffolk. His parents, Sir William and Dame Elizabeth de St. Omer, had earned the lifelong gratitude of King Edward III for their part in safeguarding the Black Prince and his sisters at a time of danger in their childhood. They were seated both at Mulbarton, and at Britford near Salisbury, Wiltshire (where Alice was born), adjacent to the royal palace at Clarendon. They were most likely the patrons of the "St Omer Psalter", an unfinished but sumptuous work of book-illumination of the 1330s-1340s. Images of the patron, in a tabard of the St. Omer arms, and his wife appear in the embellishments to the grand initial of the First Psalm. At Sir Thomas de St Omer's death in 1364 there was no male heir, and so – through Alice – Mulbarton came to the Hoo inheritance.