On the 28th March 1845, John Tawell was hung for killing his mistress. This was not an unusual conviction, but the way that Mr Tawell was caught certainly was. He had been tracked down by the use of an electric telegraph!
The Electric Magnetic Telegraph first operated between Paddington and Hanwell in 1839 and in 1843 was extended to Slough.
So what happened? On 1st January 1845 John Tawell travelled from London to Slough to visit his mistress Sarah Hart on Salt Hill. He was carrying cyanide of potassium, a deadly poison, which he gave to Sarah in a glass of stout. Sarah's screams after drinking the poison alerted the neighbours and Tawell was seen leaving the cottage and hurrying back to Slough Railway Station.
He returned to London, spent a relaxing evening in local coffeehouses before going to his lodgings for the night. The following morning the police arrested him there.