Beaming for the cameras, the proud grandparents drew up in a black taxi and entered the building via the main entrance, after being greeted by the hospital's lead clinician Jonathan Ramsay.
Beating members of the royal family - including the Queen, Prince Charles and Prince Harry - to be the first to meet the third in line to the throne, the royal parents-in-law clearly could not wait to meet the brand new Prince of Cambridge.
Dressed in a printed silk tea dress and nude kitten heels, Carole Middleton chatted briefly to a member of hospital staff on the steps, before making her way inside with her husband.
After a brief visit, the couple emerged, telling onlookers their first grandchild 'absolutely beautiful' and that the royal parents are coping 'fabulously'.
Michael and Carole Middleton's visit comes after Kate Middleton's hairdresser, Amanda Cook-Tucker was spotted entering the hospital via a side entrance this afternoon.
She was joined by an assistant to the royal couple, who was caring a tiny baby seat, and later, several dresses in covers - prompting speculation that the Duke and Duchess - and baby Cambridge - could make their first appearance as a family in a matter of hours.
Earlier this afternoon, Prince William and Kate Middleton issued a heartfelt statement from 'the three of us,' thanking hospital staff for the 'tremendous care' they had received during their stay.
'We would like to thank the staff at the Lindo Wing and the whole hospital for the tremendous care the three of us have received. We know it has been a very busy period for the hospital and we would like to thank everyone - staff, patients and visitors - for their understanding during this time.'
A royal baby announcement was made last night, which revealed Kate Middleton gave birth to a baby boy at 4:24pm yesterday afternoon.
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