In episode four Paul meets five-year-old Cora who has Cerebral Palsy. Thirty thousand children in the UK have the condition which affects coordination and muscle control. Cora's mum Poonam explains that Cora has a stiffness in the right side of her body which is causing her to limp and struggle with normal movements.

Cora is at GOSH to take part in ground breaking research which uses Botox to relax the over-active muscles. Paul goes with Cora to the sensory room to try to distract and relax her whilst she has the injections. And the programme follows Cora after the injections to see if they have worked.

Also in episode four, Paul reveals that he's developed a soft-spot for babies. GOSH treats 6000 babies every year and Paul goes to meet three-month-old Oliver who was born with a cleft lip. Paul is with Oliver as he enters theatre to have his cleft lip repaired.

Paul meets charming four-year-old Lucy, who has travelled down from Glasgow for the latest check-up to monitor her pulmonary hypertension - a high blood pressure condition that affects the lungs. He also meets remarkable 13-year-old Connor, who is on the isolation ward as he prepares for a bone marrow transplant to help treat leukaemia. As Connor needs to live in a totally sterile environment to protect his weakened immune system, Paul can only speak to him through a window - but that doesn't stop him finding a number of fun and interesting ways to keep Connor occupied during his recovery.