Little Isabelle, aged two, was born 12 weeks early and suffers with a condition called apnoea ofÂ prematurity, which makes her stop breathing without warning.
But quick-thinking Harry has learned how to perform mouth-to-mouth resuscitation at the Red Cross Teddy Bears club and regularly steps in to keep his sister alive.
Harry has performed mouth-to-mouth resuscitation on her while watching TV, during visits to the supermarket and on family days out.
Proud Maria says she has ‘no doubt’ her little daughter would have died had it not been for her big brother.
Harry first came to the rescue when the family were watching television and Isabelle cried out before turning blue and falling unconscious.
Maria, 37, said: ‘It all happened so fast and we were just thinking â€˜oh my god, whatâ€™s happening.â€™
‘She just turned blue, then purple, and she was unconscious. She was out cold. But Harry was so cool and calm. He just tapped her leg and called her name and when he got no response he just gave her two breaths and she came round and took an enormous breath.
‘We couldnâ€™t believe what we had just seen.’