Born in Winchester, Hampshire, Spratt moved to London, initially living in Edgware Road. In 1871 he married in Alice Petrie in Bethnal Green. He moved to Forest Gate where he established a draper's shop at Woodgrange Road. This became the firm of L W Spratt & Sons. He was elected as a councillor representing Plaistow Ward on West Ham Borough Council in the 1890s. He rose to become an alderman and served as Mayor of West Ham on two occasions in 1901-02 and 1906-07. When the Metropolitan Water Board was formed in 1903, Spratt was appointed to the new body by West Ham Corporation.