He is well-known for his high-profile roles in the films Elephant Man or Alien, but Sir John Hurt plays an altogether different type of character in his latest life-saving role - as a peanut.

The Norfolk-based actor is joined by David Walliams, David Mitchell and Johnny Vegas in voicing a group of characters based on choking hazards in an animated advert for the St John Ambulance, which teaches parents how to save a choking baby's life.

The charity's first aid campaign comes as it is revealed that three-quarters of parents in Norwich (73%) do not know the correct technique for saving their baby from choking, despite it being a major fear for 49%.

The celebrities play several choking hazards who are fed up with babies choking on them.

The advert will be shown on television over the next three months and St John Ambulance is asking people to share the film with their friends and family, online, so that as many people as possible can learn to save a life.

Nationally, the charity's research also showed that 53% of parents said knowing first aid would help them feel better prepared and less scared.

Of those who said they knew how to save a choking baby, only 29% knew the correct, recommended technique and nearly three quarters of parents (71%) selected the wrong answer when given multiple choice options.

Of the parents who had witnessed their baby choke, 77% said their baby choked on food, 14% on vomit, and 9% on toys.

Paul Knighton, St John Ambulance's East of England regional training and community projects manager, said: 'Knowing what to do in an emergency can be the difference between life and death, especially with something like choking.

'We all know how time-pressed parents are, so this film makes it as easy as possible to learn first aid – in less than 40 seconds we can all know a skill that could save a life.

'Our hope is that people in Norfolk watch, enjoy and share the video with their friends and family, so more of us have the confidence to act in an emergency.'

• Do you have a story about saving someone's life? Call reporter Kim Briscoe on 01603 772474.