In the short story Tape-Measure Murder, Arthur Spenlow is a resident of St. Mary Mead was married to Dorothy. He was a jeweller in London and then met his future who at that time owned a flower shop. after marriage they moved to St. Mary Mead where they lived at Laburnum Cottage. His wife was subsequently murdered and what happened thereafter forms the main plot of the story.
Mr Spenlow is described as a "small, spare man, stiff and conventional in speech, the acme of respectability".
Mr Spenlow had lived in towns all his life, and so it seems odd that he should have come to live in the country. However, he tells Miss Marple that since he was a boy, he had always intended to live in the country and have a garden of his own.
Mr Spenlow has always been fond of flowers. He first met his wife when she was at the flower shop that she was running.
Although he is interested in growing flowers, Mr Spenlow knows nothing about them. He has only a vision of "a small cottage garden thickly planted with sweet-smelling, brightly coloured blossoms". He had asked for Miss Marple's help, and noted down her answers to his questions in a little book.
When Mrs Spenlow is killed, Mr Spenlow is suspected, because it was she who had the money, and at her death, he comes into a tidy sum.
Mr Spenlow tells the police that on the day of the murder, he received a telephone call from Miss Marple, asking him to go to her house.
Many people in St. Mary Mead think that Mr Spenlow killed his wife, because he does not seem to express much grief at her death. Miss Hartnell tells people that when she told him that his wife was dead, he was far too calm, and that it is not natural for a man to hear that his wife is dead and not express any emotion.
Mr Spenlow tells Miss Marple that he was sincerely attached to his wife, and feels her loss very keenly. He mentions a story of a Chinese philosopher who, when his wife was taken from him, continued to bang a gong in the street exactly as usual, impressing the people of the city with his fortitude.
Mr Spenlow tells Miss Marple that he is thinking of having a pergola on the west side of his cottage, with pink roses, wisteria, and a "white starry flower" whose name he cannot remember. Miss Marple gives him a catalogue to look through.