Peter Vanguard is a scientist of some repute: an expert in acoustics, who once (according to Dunning) wrote an interesting paper on the property of underwater echoes.

Vanguard has read several of Dunning's novels but, like so many other people, didn't really understand a word of them. Yet this doesn't stop him striking up a friendship with the Professor when they find a shared interest in Denge Marsh's unusual history.

Vanguard is played by Jack Fox.