Before her release today Prince William visited his pregnant wife the Duchess of Cambridge yesterday evening.
He was showing his support for Kate as she spent her third day in hospital suffering from severe morning sickness.
Earlier, on a visit to Broadgate in the City of London, Prince William's uncle, Edward, Duke of Wessex, sent Katherine his best wishes.
His wife Sophie, Duchess of Wessex, said news of Katherine's pregnancy had been "the most perfect end to a pretty amazing year."
Elizabeth II celebrated her diamond jubilee earlier in the year after 60 years on the British throne.
Showing what a great husband he is, William had spent about three hours at the King Edward VII Hospital yesterday evening where the 30-year-old duchess was being treated.
The Duchess was also visited on Wednesday by her sister Pippa Middleton and their brother James.
Officials from St James's Palace have explained that Katherine is not yet 12 weeks pregnant with the couple's first child.
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