Adam Hart-Davis searches for unsung heroes of science on a trip to the Potteries, Staffordshire. Using a few pipes, a ribbon and an air pump, he demonstrates the early ideas for a voice synthesiser that were developed by Erasmus Darwin. Charles Darwin's grandfather.
Other subjects include John "Iron Mad" Wilkinson, who perfected the aim of the cannon.

Local Heroes Kit: a cheque for £9.95 payable to BBC Education, to [address removed] Or phone [number removed]. Calls charged at national rate.